I'd like to create a version.rc file without having to put in place a whole pipeline. I'd simply like for some code to run whenever Delphi build an executable in order to create that file.
I'm using 10.3.
You can use the build events for that purpose. You find those events in project options / Building / Build events.
You have the choice of 3 event groups : one before Delphi build your project, one before Delphi linker is called and one after the build is done.
In you case, you shall use pre-build events. As command, you can specify a program or batch file which will create your rc file.
The documentation is there : https://docwiki.embarcadero.com/RADStudio/Athens/en/Creating_Build_Events