To unlock 60fps one has to pass -GameTime.MaxSimFps 60 -GameTime.ForceSimRate 60 to launch params. I don't know if it works if you just pass it in steam launch params, since I tried to launch the Origin that gets installed with the game, and add launch params there. The command I had to use to launch Origin:

where USERNAME is the linux username for your system, and you also will need to change the path of proton executable in case you're not using Proton Experimental SteamAppId=1262600 SteamGameId=1262600 STEAM_COMPAT_DATA_PATH="/home/USERNAME/.local/share/Steam/steamapps/compatdata/1262600" STEAM_COMPAT_CLIENT_INSTALL_PATH="/home/USERNAME/.local/share/Steam" /home/USERNAME/.local/share/Steam/steamapps/common/Proton\ -\ Experimental/proton run "c:\Program Files (x86)\Origin\Origin.exe"