You can add skins though, if you like a skin you could definitely install that over ClassicShell.
here is the sequence to add a skin over ClassicShell :-
1. Right click Start button to open Settings
2. Switch to Classic with two columns style from Style tab (or single column if you prefer that)
3. Tick the "All Settings" checkbox at the top.
4. Go to Skin tab and choose the "X" skin.
5. Click OK to save settings.