Mission: Impossible - Fallout is the sixth in the film series, and the first with a returning director, writer-director Christopher McQuarrie coming back after the previous Rogue Nation. This picks up from there, though the introductory briefing and some allusions are probably all the catchup you’d need going in fresh. There’s actually a lot of linkage to Mission: Impossible III, as well as a small callback to the first in the run.
And it takes a classic moment from the original series, something the films don’t actually do much apart from the theme music and the super-masks.
Despite being two and a half hours long, it’s in such a hurry that the studio intro cards are sped up.
And the trailer cut is a misdirection... and there are quite a few in the film as well, aimed at the audience as well as various in-character targets.