Is there a way to enable some kind of autoupdate in the appcenter updates? I'm using Elementary OS Hera 5.1.6
AppCenter does not upgrade any packages without you asking it to.
When you boot, appcenter perform an "update" of the package cache in the background. This is the equivalent of
sudo apt update. This doesn't modify any packages, it simply contacts the software repositories to see if any newer packages are available and you will get a notification if any updates are available. After this, you can choose whether to update or not.
Read more: Appcenter Auto update