The only way I know is by using Krypton, which is 4 repositories. I named the four kdeu-something, where kdeu stands for kde-unstable, so I can force-upgrade to it with sudo zypper dup --from kdeu-apps --from kdeu-extra --from kdeu-kf6 --from kdeu-qt6 --force-resolution --replacefiles (possibly just a sudo zypper dup may suffice), and to revert back to Tumbleweed I can force-downgrade to it with sudo zypper dup --from oss --force-resolution --allow-vendor-change --allow-downgrade (as I renamed the default repo’s alias to oss). I have an old but similar explanation in My current Plasma Wayland from git :: rabbiticTranslator.
I used Krypton for a whole year like so on my main machine, switching back between the two occasionally. The only trick is you absolutely need to clear your ~/.cache after updates on Krypton. It still doesn’t change the fact that Krypton is everything from KDE built directly from git master (and therefore possibly more dangerous than a beta), but it’s definitely something you can do.