Changelists are more like splitting your local changes into several groups. The idea is that you usually want to commit only one group of changes while leaving others uncommitted. For every changed line the editor will show you whether it’s modified in scope of your active changelist or in scope of a non-active one. Also, you can easily ‘shelf’ and ‘unshelf’ a changelist.

I was actively using changelists for some time, but later switched to git worktrees instead. Now I usually have only 2 changelists: ‘Default’ and ‘Hacks - don’t commit!’.