FIDE's Handbook, D. Regulations for Specific Competitions (handbook.fide.com), includes the usual qualification paths for the 2021 World Cup, and adds a new one:- "VIII. One hundred (100) players are determined according to the Final Ranking of the Chess Olympiad 2020 open section."
The 2021 World Cup starts in a few weeks, so I added basic info about the new cycle to my index page for the World Chess Championship. I also added a new page 2021 World Cup; Sochi (Russia), VII-VIII, 2021. It currently consists mainly of excerpts from the regulations governing the tournament, but much more will be added over the next few months.