Modeling and acting are two separate fields. They work differently, they have different agent and agencies, different clients, the looks and skill sets (and training) required are different... So they should also be treated as separate. But for both you don't "get chosen" like it's a reality show or something. Both are a BUSINESS. It's not about you, it's about investing and making money. No one's in this to make your dreams come true. Understand that.
I'll start with modeling, since it's less complex. The way it works is you first make sure you have the right measurements to be a model in one of the departments. Make sure the (modeling) agency you're looking into is a legit one, then look at their website or call and ask for the requirements. If you have the right measurements, you send over a few pictures (not a resume! Models don't use a resume, they use a portfolio or a "book"!), again based on their requirements. If they're interested, they will meet with you in person and maybe sign you. In order to meet in person you obviously need to be there physically. Legit agencies are located in the big cities (like LA, NYC, Nashville, Miami, etc.). It's okay if you don't live close by when you take the meeting, BUT they will not sign you if you can't be where all the jobs are. Agencies are located in the big cities because that's where work is, where their clients (advertisers, designers...) are. Sometimes you will be required to travel for photoshoots, but in general you need to be where the industry is located. If you can't make it to work or to a go-see in time, that means you can't get (hired and) paid which means the agent will lose money on you. If that's the case, they don't want you. Agents make money when their clients book a job. That's how they pay their rent.
So to answer your question, you must (relocate and) live in one of the big cities, where your agency is located. It wouldn't make sense otherwise. Theoretically, as there are no guarantees, If you do well as a model, you will get better and bigger jobs. That's the order of things.
As for acting, it wouldn't make sense either, for the same reason. The entire industry is in LA, with NYC close behind and more for theater work. Other big cities have their own industry, mostly for local stuff. If you're interested in local stuff or things that don't require an agent, like theater, that's not a problem. If, however, you're interested in national movies, TV shows, commercials, etc., you have to be where work is. Simple. But can't just sign with a (talent) agency. They don't take on amateurs or beginners, only highly-trained and highly-experienced people. Productions invest TONS of money and they need to know it's in the hands of people who know what they're doing. Agents wouldn't risk their own reputation with casting directors. Since you're asking that question it's obvious that you don't have the training and (at least enough) experience. They teach you that sort of stuff in top-quality acting schools (also located in the big cities). Which is what legit (talent) agents require as your training, among other forms of training, in addition to low-level experience such as student and indie films and theater, in leading roles, as well as awards for your acting, as well as (training for) special skills such as signing and dancing, dialects, horseback riding, acrobatics, martial arts, etc.
In other words, you first need to build a resume strong enough to impress potential agents, not just a "resume." In addition to all of that, you need to network and make connections. That's how you get an agent in the first place. Other ways, like cold querying with your headshots and resume or getting spotted at a showcase, rarely work. At some point someone you've worked with and impressed (like a director, a producer, an acting teacher or even a fellow actor) might be willing to refer you to an agent. I doubt you will be able to make the connections if you're not where the industry is. That's where your connections live and work after all. While you don't need to be there while you work on your resume, once you've got a strong one you WILL have to relocate to (the very expensive) LA or NYC and continue getting more experience and training there (and work at your day job at the same time) until someone will be willing to refer you to an agent. IF an agent signs you, you will be able to start going to auditions for professional work (the way Katrina explained), when and if it there are any for you. Theoretically, as there are no guarantees, If you do well as an actor, you will get better and bigger roles. That's the order of things, in short.
Needless to say I hope, if you don't have what it takes (like the talent, the looks, thick skin, determination, passion for the craft, maturity physical and mental health, money...) don't bother. They're both very difficult jobs just to try and get into, and like I said there's no guarantee anything will come out of it.
What I strongly suggest is that first, before you invest a lot of money, time, and work and make big sacrifices in your life, you find out if it's even worth it. Learn about the realities of each job and its business. Do your research. Give yourself a reality check. See what pursuing a professional career actually entails. Learn how to recognize scams. The reality is VERY different from what people imagine and you might be more interested in a fantasy of what you THINK it's like. There's also so much more to it than most people assume.
Aside from research, if you're interested in acting and you've never tried real acting before, get into some local acting classes, something low-key just to get a sense of it. Find out what acting really is. See if you're even good at it. See if you enjoy the process. See if you can commit to many years of it. If you find that you are good at it and it is for you, apply to a good acting school (where well-known and respected acting teachers teach and successful actors graduated from) and start working on that resume. Considering agencies and relocating, even fantasizing about it, is pointless for now.