Deadpool is a part of the MCU already. Ryan Reynolds confirmed this last year while doing press rounds for Free Guy. Having said that, most presume that Deadpool 3 will be part of the MCU's Phase Four. However, with a little over half-dozen films lined up ahead of the threequel, fans shouldn't expect the R-rated film to drop anytime soon.
There's no word yet as to when Deadpool 3 will officially start filming, but THR is reporting that Marvel Studios is negotiating with Shawn Levy to spearhead Deadpool 3.
It appears that Levy's string of successful light-hearted comedy movies starring Ryan Reynolds played a huge role in this as Levy and Reynolds worked together on Free Guy, which is getting a sequel, and The Adam project. Before working with Reynolds, Levy is best known for his work on Real Steel, starring Hugh Jackman. With Levy in tow, some fans couldn't help but feel excited at the prospect of Levy bringing Hugh Jackman in to finally do that Wolverine cameo.