It’s important to note that all of these changes are only for followers you bring into combat; crafting thralls are unaffected and will not be changed or limited, so you needn’t fret about that. But if you bring your followers into combat, they’ll be able to level up to 20 and become far more lethal in combat, a nice chance to make your individual followers more unique when the system is fully rolled out to the game. And since it goes hand-in-hand with the update bringing mounts into the game, well, that should help motivate you.

Content retrieved from: https://massivelyop.com/2019/11/05/conan-exiles-details-follower-leveling-and-follower-limits-coming-to-the-game-alongside-mounts/.