The topic has come-up before, with varying results.
In 2017 (McVay's 1st season), the Rams' final game was meaningless and McVay started Sean Mannion and an OL that included Darrell Willimas, Cornelius Lucas and Aaron Neary. On Defense, Donald, Brockers and Quinn all sat. The Rams came-out flat the following week at Home against the Falcons, and lost. Many were critical of McVay's decision. I believe he also questioned wether it was wise to sit so many veterans.
Other Final Regular Season Games ...
McVay played all of his starters in 2018, when they were 12-3. Not sure if that was a meaningful game.
In 2020, the Rams needed to win that final week, so the starters played.
In 2021, the starters all played (OT loss to S.F.) but I'm not sure whether that was a meaningful game.
If I remmember last year correctly, the playoffs were secured (certain of that) but I don't believe the playoff-seeding was established. Stafford, Kupp, Willaims and Donald rested but most of the starters were in the game, including Nacua (seeking rookie records before coming-out) and the O-Line.
Clearly, any beat-up guys, playing through something should ... and likely, WILL ... be rested.
Any exhausted players, who have seen a recent decline in performance, should get reduced snaps.
However, whether healthy guys are rested is McVay's decision.
The only certainty ... For Me ... which is why I am not expressing an opinion, is that should the Rams not play well in the Wild Card Round, or get-off to a poor start, there WILL BE Criticism for McVay's decision REGARDLESS of what that decision turned-out to be.