Tomb Raider games were just recently updated to have the “multiplayer infrastructure use Epic Online Services”.
However, simply launching the games, now requires you to use an EGS account to play.
Link to the respective updates for each game
Tomb Raider (2013) https://store.steampowered.com/news/app/203160/view/4822784632077019228
Rise of the Tomb Raider https://store.steampowered.com/news/app/391220/view/4733838539436417303
Shadow of the Tomb Raider https://store.steampowered.com/news/app/750920/view/5458918080782059550