Resize VDI Image for VirtualBox
So I was trying to resize a VDI image for VirtualBox, and this is the best solution I have found: Resize VirtualBox Disk Image – grow, expand, increase a .VDI disk image in 1 minute
TLDR version of it is to run the command (on Linux) VBoxManage modifyhd ./YOUR_HARD_DISK.vdi --resize SIZE_IN_MB
For more details check out the site!