KDE Neon used to do this. Almost always caused issues after update with stuff crashing due to mismatch of versions talking to each other over D-Bus and such.
So they moved to something more like the Windows style, where it downloads, reboots to apply and then reboots again freshly updated.
So they moved to something more like the Windows style, where it downloads, reboots to apply and then reboots again freshly updated.