Doom Eternal, unfortunately, does not support Cross Platform play. For players who were excited to play with their friends, this is disappointing news. If you are looking. No it doesn’t have cross platform multiplayer. The app itself says xbox cross-platform multiplayer, but everywhere else i read that the PC can't play against xbox. CAn I play against steam.
Doom Eternal Multiplayer Cross Platform
The only "cross-play" that exists is between Steam and Bethesda Launcher players. None of the other platforms can play together. It's also never been mentioned as a feature they plan to add.