Fan-favorite actor Ryan Reynolds will once again step into the role of the Merc with the Mouth in the forthcoming Deadpool 3. Although not much is known about the film, it is all but confirmed to take place within the MCU.
Considering that the previous two Deadpool movies were set in what was ostensibly the 20th Century Fox-produced X-Men universe, this jump could be seen as a definite change of pace for the character. Of course, none of that will likely matter to Deadpool, in-universe. Since he's fully aware of his status as a character in a movie, his universe hopping is just more of an opportunity to make jokes.
Marvel Studios is known for keeping all of its various projects adhered to a sort of "house style," meaning that it all needs to look and feel like it's in the MCU. Directors have also been expected to play by the rules to a certain degree, although those reigns have loosened considerably in recent years.
Ultimately, MCU directors are given a lot of leeway in where they take the stories and characters at their disposal as long as everything ends up the way it's intended.
This "hands-off" approach by Marvel has been discussed by many individuals behind the scenes in their productions, including those of certain upcoming movies.
Deadpool 3's Rhett Reese on Marvel's Supervision
In an interview with Discussing Film, Rhett Reese, a co-writer on Deadpool 3, discussed Marvel Studios' lenient sense of oversight on the sequel, saying the studio lets them "do what we do:"
"It’s almost like putting on a comfy old sweater. Marvel’s really given us the support to maintain the tone and the vision that we have for it. They’ve been very hands-off and supportive, but they’ve also let us do what we do. So really, it’s just been fun. We’re mad scientists back in the laboratory again. Deadpool is our favorite who will always be the character I think we’re most associated with, and we’re very grateful for being allowed to write him again. So it’s a blast. It’s like going back to school again after having summer off. It’s pretty fun."
Kevin Feige & Marvel Studios Show Some Leniency
In the early days of the Marvel Cinematic Universe, things were much more ironclad and regulated. In fact, Iron Man director Jon Favreau had a falling out with Marvel for a time due to the studio trying to put too much Avengers setup into Iron Man 2, which Favreau also helmed.
This was all likely due to the fact that Marvel as a whole was still under the thumb of Ike Perlmutter, who tried his best to force the company to conform to his ideals, which were often frugal. Additionally, the infamous and now-disbanded Marvel creative committee had a lot of final say in what could be put into an MCU movie and what had to be left out.
Eventually, of course, Marvel Studios president Kevin Feige grew tired of all this and requested that Perlmutter and his ilk be shunted off to roles that would not interfere with the operation of the movies' productions.
Nowadays, as evidenced by Reese's words, Marvel has become much laxer about overseeing its productions. What's more, the studio is "supportive" when it comes to filmmakers' input in the overall direction of their movies.
This is not to say that Marvel still doesn't lay down the law when it needs to. It was recently revealed that Taika Waititi was capped at a two-hour run time on Thor: Love and Thunder and not allowed to go beyond that. But overall, it would appear that as long as directors put all the toys back in the right places, they're allowed to play in the Marvel sandbox.
Marvel Studios' Deadpool 3 does not currently have an announced release date and is in development.