how do we use 32 bit again on mac os catalina

Should your Mac still run earlier macOS than Catalina, the matter of reverting may not

be as difficult as after Catalina macOS10.15.7. And Mojave macOS 10.14.6 still works fine.

• Revert your Mac to a previous macOS version - Apple Support (defaults to 10.15.x)

https://support.apple.com/guide/mac-help/revert-to-a-previous-macos-version-mh15216/10.15/mac/10.15

This article can be useful across latest (as of now) three macOS build versions available

as it can be 'toggled' to see: High Sierra, Mojave, and Catalina information instructions.

Good luck & happy computing!🌻|🐝

You determine if the original developer provides those applications as 64-bit, and compatible with Catalina. If not, you are done with those apps on Catalina.

You cannot run 32bit apps in Catalina.