# We need to resize the logical volume to use all the existing and free space of the volume group
$ sudo lvm
lvm> lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
lvm> exit

# And then, we need to resize the file system to use the new available space in the logical volume
$ sudo resize2fs /dev/ubuntu-vg/ubuntu-lv
resize2fs 1.44.1 (24-Mar-2018)
Filesystem at /dev/ubuntu-vg/ubuntu-lv is mounted on /; on-line resizing required
old_desc_blocks = 1, new_desc_blocks = 58
The filesystem on /dev/ubuntu-vg/ubuntu-lv is now 120784896 (4k) blocks long.

# Finally, you can check that you now have available space:
$ df -h
Filesystem                         Size  Used Avail Use% Mounted on
udev                               3.9G     0  3.9G   0% /dev
tmpfs                              786M  1.2M  785M   1% /run
/dev/mapper/ubuntu--vg-ubuntu--lv  454G  3.8G  432G   1% /

If on TrueNAS

sudo cfdisk #resize it in there
sudo pvresize /dev/sda3 # or what ever the PV is on
sudo lvextend -l +100%FREE /dev/ubuntu-vg/ubuntu-lv
sudo resize2fs /dev/ubuntu-vg/ubuntu-lv