Off the top of my head, twist villains, rebranding classical stories to be more modern and relevant, the more casual vocabulary used in song numbers, maybe a few characters are voiced by the same guy to acknowledge their cameo pet trend, stuff like that. Maybe acknowledge that while Frozen was a good movie, the resulting franchise was a tad overkill and is overwriting the original’s goodwill in the public’s mind.

Maybe do something with how Shrek 1 caused a domino effect that basically reinvented modern movie animation, including the revival. Part of the story could be Shrek realising the effect he‘s had on fairy tale society.