As you probably noted with the post about Plasma Bigscreen, Plasma 5.26 testing has started in the [kde-next] repo, see the release today of Plasma 5.25.90 (5.26 Beta). Final release is planned for three weeks from now.
As always, place kde-next above all in your pacman.conf. If you do not know how to edit pacman.conf, then please don't try to attempt testing betas of Plasma, editing the pacman.conf is the easiest part of this kind of testing.
A test ISO with Plasma 5.26 Beta is uploaded (also a first ISO uploaded that uses Dracut for initramfs creation, instead of Mkinitcpio).
The ISO uses the [build] & [kde-next] repository, so best to use it just fro Live mode, so you can see 5.26 in action.
https://sourceforge.net/projects/kaos-test/files/iso/KaOS-2022.09.16-x86_64.iso
Current stable ISO (available from the Download page) includes Plasma 5.26RC.
SHA256SUM:
65f25c3e0b91d0d33c48d3fea2663b17b20ba0e5c0b4e3e892e339e3616a3730 KaOS-2022.09.16-x86_64.iso