Does not accepting all federal financial aid offered to you reduce the amount of future financia aid

No. Do NOT accept PLUS loans if you don’t need them. The ‘government’ doesn’t interpret anything. Your school gets the FAFSA report and administers the loans.

If you are offered work study and do not use it/accept it, you might be offered less in the future because schools do want to award (and have used) all the funds. Usually you can get it reinstated if you had a good reason for not using it.