Right-Clicking a Source Clip, you should be able to Paste and Remove Attributes, the same as you can from a clip on the timeline.
Backstory:
We shot a short video in Anamorphic on the Sony a7siii into a Ninja V+ and loved most of the results. In the source clip from the bin, we changed the PRORES RAW Source Settings to the appropriate Color Space, but to desqueeze, we added a Transform Effect on the source clip to make it less complicated if we wanted to add any effects to the edit, later. We were able to copy both Source Settings and Transform effect and paste them to the 58 clips. The problem is this: when we started to denoise some darker shots and color correct, we realized our aspect ratio looked off. We went back and found we had put in the wrong desqueeze setting on the transform. The solution? Double click each clip, delete the old transform effect, and add the correct transform effect: fifty-eight times. I just kept thinking - how is this not a feature already?