Is it OK to take SATII or SATI in the fall of my senior?

I know its too late. But I’m not satisfied with my SAT score so I’m planning to take it on may of my senior and also I want to take the SATII this june…

Would it do any benefit for the University?

If it’s after the application deadlines, then no.

Acceptances have already been sent, so, no.

Well if there’s rolling admission and you haven’t applied yet then it could make a difference…

It will definitely be too late to help with admissions, but some colleges will increase your merit scholarship if your scores improve.

Some schools accept the January SAT.

The only ways I could see this benefiting admissions is if the school you’re applying to has rolling admissions or if it’s a part of your conditional offer (mostly applicable to UK schools I believe).

It’s only beneficial if you take SAT Subjects in subjects where it would waive the placement tests and/or get you credit (ie., in math and foreign language, typically).
However, SAT1 is of NO USE once admissions have been announced.