Valve has delivered an OS update which adds native ray tracing to the Steam Deck. The first game benefitting from this change is DOOM Eternal. At the time of writing, the necessary Steam Deck OS update is a beta, version 3.4.6 Beta to be precise, so some will prefer to wait for a mainstream update before testing ray traced DOOM Eternal on

Source: Hot Hardware – How To Enable Sweet, Shiny Ray Tracing In Doom Eternal On Your Steam Deck Console