If I install the 15.2 beta would it just update to the stable version when it’s released?
Not quite.
You need to run:
zypper dup
from a root command line. If you install the beta (or release candidate which should be out soon, then I suggest using that “zypper dup” from time to time – maybe weekly, until the final release. Then maybe do that once more to be sure that you are at the final release.
After that, resume normal update procedures.
Which reminds me – it is time for me to do a “zypper dup” on the computer where I am typing this.
Just seen the following message with additional details:
https://lists.opensuse.org/opensuse-factory/2020-05/msg00254.html