In System Settings -> Login Screen -> Shutdown we can select boot manager to get ability to select where to boot after reboot. But it didn't support UEFI yet. But using "efibootmgr" we can select our next boot via "--bootnext" command. It will be very usefull.
Did this fit your needs? https://www.phoronix.com/scan.php?page=news_item&px=KDE-Plasma-5.16-Reboot-To-UEFI
Yes, this feature was added in the Desktop Sessions KCM in Plasma 5.16.