All 3 of the Tom Holland solo Spider-Man films are going to feature the character during his high school years; this was confirmed months ago.
This means that the second and third solo Spidey films will unequivocally break the MCU cycle of each film being set in the year in which it's released since they're going to have to be set in 2018 and 2019, respectively, in spite of the fact that they'll be released in 2019 and, presumably, 2021. It also means that, for Marvel Studios' part, the second Infinity War movie, if it includes Spider-Man, may end up referencing events that we as an audience haven't yet seen.