WWE has at least discussed the possibility of having Roman Reigns wrestle on both nights of WrestleMania 39 - with Cody Rhodes and Dwayne 'The Rock' Johnson standing as potential opponents.
Dave Meltzer reports in the Wrestling Observer Newsletter that while this has been talked about internally, the current "best bet" is that things won't play out this way. Nothing is set in stone when it comes to Roman and WrestleMania, however, and Rhodes and Johnson have been heavily rumoured as potential 39 opponents for the Undisputed WWE Universal Champion in the past.
Beyond 'Mania, WWE has also talked about splitting Reigns' two championships up so that Raw has a top belt of its own. Reigns, a SmackDown wrestler, unified the Universal strap he already held with the WWE Championship by beating Brock Lesnar at WrestleMania 38 in April. He has since defended both straps as one.
Meltzer writes that WWE must finalise its plans by mid-January, doing so ahead of Royal Rumble 2023. The winner of that bout would typically be expected to challenge for a top title at 'Mania.
Roman is comfortably the longest-reigning World Champion in modern WWE history, having held at least one version of a top title for 831 days.