GOG is offering a FREE Copy of The Witcher: Enhanced Edition when you download GOG GALAXY through January 5th, 2022. Go here then scroll down and click on "CLAIM NOW". You can also claim a pack that includes arts, books, soundtracks, the making of videos, Video Game Show concert, wallpapers, and many more goodies from all The Witcher games gathered together! Just click on "CLAIM FREE GOODIES" on the same page linked above.
In order to claim your copy of The Witcher: Enhanced Edition, you need to log in to your GOG account through GOG GALAXY, and click on the giveaway banner on "Recent" view. The gift won't be available if you already own The Witcher: Enhanced Edition in your GOG library.