Question about sharpness and scaling

I have UHD clips in a HD timeline and I plan to zoom in somewhat (as discussed elsewhere, this is just recovering some of the source resolution, as long as I don't zoom in past the HD crop in the UHD source), but since the UHD source is somewhat soft, I'd like to add some sharpness: will sharpness be added at the source res, or at the timeline res ? IMHO the former would potentially yield more interesting (subtle) results...

Clip effects work on the original clip.

you are sharpening at the original resolution IIRC.

however, in resolve 17 there are more option of scaler algorithm (in case you are on 17) that can help.

bare in mind that "sharpness" is just contrasting edges: if you are either really out of focus or you're really push the size, there is a point where the resolution fo the lens is simply not enough.

helpful, thanks