Date: 2018may2 Updated: 2023may10 Q. Virtual Box: how to grow a virtual disk A. Surprisingly, this isn't available in the disk settings for the VM. Instead from the main menu

File > Tools > Virtual Media Manager

And right-click on your virtual disk for a menu. Next, you need to grow the guest filesystems. You can boot the Gparted bootable iso in Virtual Box.

Controller: IDE (Your gparted .iso) Controller: SATA (Your guest disk image - might be .vdi)

Or, use commands while in the guest OS. On Fedora I successfully did:

# parted print all Lists all partitions and I see I want 2 larger resizepart 2 100% write quit