Linux provide the facility to increase the size of a volume group even if it already exists. For this, we need to run a command.
First of all, we have to create a physical volume (/dev/sda1)
Size of the physical volume should be the size you want the size of the logical volume.
Now, run the below command:
vgextend VG1 /dev/sda1
Here VG1 is the name of the volume group.