Trump didn't double anything. Congress makes the laws. The president can advocate for things but can't put them into law until Congress passes them.
The standard deduction wasn't quite doubled, but the child tax credit was doubled, and for all families with children that qualify for this credit, with the exception of a very small number of upper middle class earners, that doubled child tax credit, combined with the higher standard deduction, more than made up for the elimination of the personal exemptions.
The claim is that this didn't help the 'poor'. Well, of course it's not going to help those who are already paying no income tax. A majority of the middle class was helped.
Except that it DID help the 'poor'. For the first time, a portion of the unused child tax credit is refundable. Previously, only the earned income credit gave people who owed no income tax money back - a wealth transfer and nothing more. Now, if some of the child tax credit takes your tax to zero, some of the credit you didn't use can be 'refunded' to you.