The GOG version of Fallout 4 is currently locked to 1.10.163, making it a popular alternative for players who want to avoid automatic Steam updates.
Open the Steam Console by typing steam://open/console into your web browser or the Windows "Run" command (Win+R). fallout 4 patch 110 163
Set the file appmanifest_377160.acf (found in your steamapps folder) to Read-only to stop Steam from overriding your version. The GOG version of Fallout 4 is currently locked to 1
