Answer by Gino Mempin for How do I check whether I am using LVM?

In particular, can I see it in GParted Partition Editor ?

Yes, you can also see it with GParted.

LVs will show up as a "lvm2 pv" File System.
It will also have a "lvm" flag.

On right-click then selecting Information, it will also show:

This is on Ubuntu 18.04.4 LTS and GParted 0.30.0.