Offer pre-configured Gallery VMs with more virtual hard-drive memory (or simplified instructions on how to download a linux distribution and use it to create a new VM for novices)

I’m finding that I’m running out of room quickly on the pre-configured Debian XFCE VM I downloaded from the gallery and understand from online conversations that it is not a straightforward task to expand a VM hard-drive after the VM is configured. Could someone offer pre-configured VMs with more virtual hard-drive memory? Alternatively, could someone provide some simplified step-by-step instructions for novices on how to download a linux distribution iso image and use it to set up a custom VM on UTM? I tried following online guidance on how to download a Debian iso and tried to mount it and use it to create a virtual machine (similar to what worked and how UTM suggests downloading a Windows iso image to set up Windows UTM), but it didn’t work (didn’t seem to get proper installer screen to install). Thanks for considering!