downgrading within catalina

Is it possible to downgrade Catalina versions example

if I order a Mac that ships with Catalina 10.15.5 can I downgrade it to Catalina 10.15.3 etc

I am under the impression it is impossible and or extremely difficult to downgrade a new Mac to an older os ie 10.14 but can you downgrade within Catalina.

I just purchased an imac and run pro tools that as of right now is only optimized for 10.15.3 not 10.15.4

I posted yesterday and found out that there is no way to determine what version of Catalina is preinstalled until boot.

thank you in advance!