A possible synopsis for the threequel recently found its way online which reads, "After facing some professional setbacks while going through a midlife crisis," it reads, "Wade Wilson decides to officially retire Deadpool and becomes a used car salesman."

Source: https://comicbookmovie.com/deadpool/deadpool-3/deadpool-3-star-ryan-reynolds-shares-a-new-look-at-wade-wilsons-comic-accurate-suit-for-the-mcu-a208606

James Spader's Ultron, on the other hand, is a much stronger choice: both because he hasn't squared off against Wade Wilson onscreen before, and because he's a much better fit for the project.

Source: https://www.cbr.com/wade-wilson-fight-ultron-deadpool-3/

Ryan is set to reappear in his role as Wade Wilson for 'Deadpool 3', and Hugh Jackman will return as Wolverine in the upcoming sequel after last featuring as the mutant character in 2017's Logan.

Source: https://www.hertfordshiremercury.co.uk/news/hertfordshire-news/hugh-jackman-ryan-reynolds-spotted-8599630

This will not be the first time that Reynolds plays Wade Wilson amid a writer's strike, as the actor, and Jackman as Wolverine, had to deal with an absence of writers due to another WGA strike while shooting 2009's X-Men Origins: Wolverine.

Source: https://screenrant.com/deadpool-3-filming-start-ryan-reynolds-improv/

Wade Wilson is a foul-mouthed character, and it's long been known that Reynolds' will be the MCU's first R-rated movie, so it will no doubt include a lot more than a single F-bomb.

Source: https://screenrant.com/marvel-first-f-word-guardians-of-the-galaxy-3/