Upgrade to 32 bit

Thanks for the wealth of information in your enquiry.

All macs have been 64bit for over 12 years approx, with the introduction of

macOS Catalina, later versions of macOS like Big Sur these OS's will not run

64bit apps.

If you are planning on upgrading your macs OS then you will need to know which third party apps

you have are 32bit, use this free app, https://www.stclairsoft.com/Go64/

Having noted which 32bit apps you have contact the apps developer to see if they are offering 64bit updates.

32bit is not an upgrade. 32bit software support ended with macOS 10.15 Catalina.