Linux Shout published a tutorial about installing VirtualBox Guest Additions on AlmaLinux 8.

How to install VirtualBox Guest Additions on AlmaLinux 8

After installing AlmaLinux or any other operating system on Virtualbox, it not going to adapt the screen size automatically. Instead, you would have a scaled-down display which doesn’t give a good experience to users. Moreover, also some other features of VirtualBox such as Host to Guest drag and drop shared clipboard, and copy-paste will not work as well. To get these features along with the optimal performance for the Guest, we need to install VirtualBox Guest Additions ISO on AlmaLinux. Well, VirtualBox already comes with an ISO file that can be easily mounted in Guest OS to install VirtualBox guest

How to install VirtualBox Guest Additions on AlmaLinux 8 - Linux Shout