There have been reports but Kevin Feige has not confirmed whether there will be a trans character in the Marvel Cinematic Universe, sources told Variety.
Feige was participating as a guest lecturer for New York Film Academy in Los Angeles in December. There he was asked if the studio will debut more LGBT+ or trans characters into the MCU. He said that they will and they are shooting the film currently.
Although his reply to the question looks like he is responding to both the options. But he meant to respond to the LGBT+ part only. He did not mean to imply any trans character was in the making.
Currently, the MCU movie under production is Eternals which is being directed by Chloe Zhao.

The film was confirmed in August by Feige. The movie stars Richard Madden, Salma Hayek, Gemma Chan, Kumail Nanjiani, Kit Harrington, Barry Keoghan, Angelina Jolie, and Brian Tyree Henry.
The movie will have the first gay character of MCU. Feige did not specify who would it be.
The debut of an openly gay superhero is a major milestone for Hollywood. Hollywood has been putting it off for quite some time now.
It is about time that a gay character will be front and center in a major comic book movie. Star Wars: The Rise of Skywalker had its first same-gender kiss on the screen. It was praised a lot.
A throwaway for it was that it was between two minor characters. Feige has said that the gay character in Eternals will have a meaningful role.
Feige told Good Morning America that the character is married, has a family and that is a part of who he is.
Zach Barak had a small role in Spiderman: Far From Home and he was the company’s first openly trans actor.
There will be a gay character in the MCU but it looks like that debut of a trans superhero character would have to wait.