Every play is different. Whoever is the furthest player to his side(a TE, another WR) is going to head out to block the defender who is manned up on the WR, and their are offensive linemen headed out to head off the linebackers and possibly safeties, but usually the first blocker(WR or TE) springs the WR free on an outside screen and he makes other defenders miss. It seems to happen with 2 or 3 players split out to one side usually, to give the player a couple lead blockers.

An inside screen sometimes happens where it’s a slower developing screen with a WR(similar to a TE or HB screen) and the WR runs in towards the middle of the field while the QB drops back. The OL heads out to the second level, allowing the DL to get past and the WR catches the ball behind the LOS, then turns upfield picking his way through the clutter of blockers. I haven’t really seen that in the NFL I don’t think, WR screens don’t happen that often, and the ones I’ve seen are on the outside with a TE or WR out their with them.