Judging by the timeline, Peter should NOT be 16 in this movie.
There's no way in hell that Peter only aged one year from Homecoming to Far From Home. Homecoming took place in 2016 and Peter was 15 in that movie. Infinity War took place in 2018 meaning that Peter should be 17 years old in that movie. Peter blips out at the end of that movie, comes back in Endgame 5 Years Later and Far From Home takes place 8 Months after that movie. Peter should be getting closer to 18 (if not already).
Another thing, shouldn't Brad be out of High School? High School is 4 Years, not 5 Years (which is how much time has passed between Infinity War and Endgame) and according to the dialogue, they were all aware of Brad before they all got blipped as if he went to school with them. How?