Are interest amounts calculated based off of yearly total amount borrowed, or only on the amount that has been disbursed?

I'm borrowing about 25k for the upcoming school year. (my cost of attendance is 27k but I get about 2k from scholarships).

5.5k of this is covered by unsubsidized federal loans.

The rest I am considering either a private loan from SoFI or ask my parents to take out a parent plus direct loan. However, I had a question.

With SoFI, the interest accrues immediately on the total ~20k even though I am going to be paying only half of that each semester. I thought this was somewhat unreasonable.

I am wondering if the federal direct parent plus loans also act like this? Or will the interest only accrue on the amount that is actually borrowed each semester?