First, use fdisk/gdisk/similar to resize partition to fill disk. This can be done by deleting the partition, then recreating it, taking special care to ensure that the first block is the same in the new partition.

Then, use the following commands. Example data is given, you may need to adjust to fit your situation:

pvresize /dev/sda3
lvextend -r -l +100%FREE /dev/mapper/pve-root