=====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