Simple Extend in place

Extend the main 1st Logical Volume by 500G and resize in one step 

lvextend -r -L +500G /dev/ubuntu-vg/ubuntu-lv

Complex Extending LVM

Create new parition on the physical drive: 

sudo fdisk /dev/sda
n, then p (primary), then size accordingly
then w to write changes

Add new extent to Volume Group 

sudo vgextend rootvg /dev/sda4

List Logical Volumes 

sudo lvdisplay

Extend the logical volume 

sudo lvextend -L +100%FREE /dev/rootvg/varlv

Check Filesystem 

df -Th | grep "^/dev"

Grow the ZFS file system 

sudo xfs_growfx /dev/rootvg/varlv

Grow the ext4 file system
resize2fs /dev/rootvg/varlv