Doom: Eternal has a variety of different skins your Doom Guy can wear during their single-player adventure. You have a handful you can obtain by traversing the Fortress of Doom, and some of them can be earned while playing the game during the current series’ lifetime by reaching level 10. There are several different zombie-like skins available for the Doom Guy and several demons you can play online.
To obtain these skins, you need to join Bethesda’s slayer club online. You can join the club on Bethesda’s website and you can start leveling up your account, for free. All you have to do is play Doom: Eternal while logged into the account.
There are several rewards available. The first reward you receive at level one is the zombie Doom Slayer skin, for your Doom Guy. You can play it on in the customization menu on the main screen. Later, you can eventually earn zombie skins for the Mancubus, and an Imperial Marauder skin, and the final, level 15 reward is the 25th-anniversary Slayer appearance.
Make sure to log onto Bethesda’s website to start earning experience points. There are 15 levels in total for you to earn.