You might already know about the easy button. The diagnostics option is when you manually trigger a pipeline. Are you debugging a pesky pipeline and tired of manually triggering it?
Background
The diagnostics option is found when queueing a new build.
Then from the pipeline output, you can see more verbose logs in pretty colors.
Again, but it can be quite tedious when troubleshooting something intensely.
Permanently
To do it permanently, you can simply set system.debug as a pipeline variable.
variables:
System.Debug: true
Or you can set it as a separate variable that won’t get source controlled. But it’s probably more effective for secrets really.
If it were me, I would probably forget to remove it.