@user-OHTrLNQCsZ Take a look at https://github.com/moorereason/make_ge_version_regex/. It will create a regex that will match a specified version number or higher, and if you use "does not match regex" as the operator in your Smart Group it will match applications versions less than the specified version number.
This Match Version Number of Higher.bash script from William Smith generates a regex for the version you specify or higher. The script generated the following regex:
In your group or search, you can set the value to does not match that regex.
Edit: I did not see @sdagley's post until after I posted this.
So many ways to skin the cat. My brain has an easier time when I first define the "desired state" version (2.13.210200), and create the regex in a way that covers that version and higher. This way I can use "Does not match regex", where the regex covers the desired state and higher.
I use https://regex101.com to create the regex and test. Since regex analyzes a string, there's no need to check the entire version, just go from left to right, and stop when you've confirmed the portion of the string meets the requirements.