Solomani,
Check out some of the modules for the D&D , Masters, Companion, and Immortal editions (BECMI). These were designed for ultra high level characters. Of course you will have to adapt them to 5e.
CM1: Test of the Warlords has the party fighting an army of 400 Frost Giants in one encounter. Sounds like a good romp for some superheroic characters!
The H-series, set in the Bloodstone lands ends with the characters fighting Orcus. The last module H4 The Throne Of Bloodstone is for character levels 20-100.
Q1: Queen of the Demonweb Pits, was TSR’s first foray into godslaying. It took the party to the abyss to fight Lolth, who was pretty weak by “god” standards (66 hit points). It nerfed most of the player’s spells and magic items.
Pathfinder published the stats for most of the Great Old Ones from the Cthulhu Mythos in Bestiaries 2-onwards... You can convert them to 5e and drive your players insane.
You could check out adventures for Amber Diceless system. In Amber, the player characters were godlike beings. Challenges were abstract since most things a godlike player character would attempt, they would be successful at. So you have to trick them into screwing themselves.