Custom gcode in "Prepare/others/Post-processing

In SlicR , the mother of all slicers, then prusa, SuperSlicer, Cura etc… it was possible to add custom Gcode which was then incorporated into the slicing.

e.g. if {layer1} [M221 S120] which means if the layer is 1 then set the flowrate to 120, then of course reset it in the next layer. The syntax may be incorrect
This is not for beginners, but Chatgpt told me this was not possible. But Chatgpt makes mistakes, maybe someone knows?

You can add post-processing scripts in “Others” tab of bambu studio

Please give an example, do you have one?

I don’t use it and I wouldn’t want to make one up that could wreck anything but your question was not to give you one example but something you had in other slicers you could not find an equivalent in studio, that was the answer.