SQL 2012 Dev should have no impact on other versions of SQL. You didn't post any error information or setup logs so we have no real way to help you at this point. You can install SQL Server 2019 Express on any machine that meets the requirements irrelevant of other SQL Server installs.
Installing Sql Server 2019 Express

I received an error when installing Sql Server 2019 Express. I have Sql Server 2012 Developer installed which was not updated in 7 years. I downloaded the latest 2012 updates and tried to reinstall 2019 but the error was not resolved. My Windows 10 uses 64 bit and my Sql Server 2012 was 32 bits. What do you suggest
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Erland Sommarskog 72,971 Reputation points MVP
2022-08-12T21:36:45.543+00:00 Did you try to install a new instance with SQL 2019 Express Edition? That should work, regardless which other instances you have on the machine.
IF you ran into errors, we need to see error messages and log files.Or did you try to upgrade the existing instance? I don't know for sure, but I would not expect it to be possible to upgrade a 32-bit instance with a 64-bit version.
Either uninstall or install a new instance. The latter may be better so far that it makes it easier for you to copy databases, logins etc. Once you have the new instance running, you can uninstall the old one.
Keep in mind that if you install a new instance, you need to update connection strings to point to the new instance. If you want to deal with that uninstall + install is better.