Multicam - shot in DCI 4k delivering in 1080

It's been a while since I dug through the forum as there wasn't an answer to solve this previously. I create Multicam sequence from 3 sources of DCI 4k footage, and the Multicam is set to DCI 4k as well. I place that into my 1080 timeline and make my mutlicam selects, however since the resolution mismatch I get black bars on top and bottom. Is there no way to scale this to fit my frame without flattening or scaling with zoom above 1?

If this is by design, I need clarification. How do I fill the frame with mismatched resolution. I'm recording in a higher frame size than needed, then multicaming in a 4k DCI timeline, and then placing that in a smaller timeline (1080)) so I can scale up in the edit. But I have to manually touch every single clip because Resolve does not scale properly in the 1080 timeline. I feel that the fundamental system behind the "resolution independence" is flawed in Resolve. Flattening multicams so I can correctly zoom ".5" on a 1080 timeline is not efficient or effective.

Are you intending to "punch in" to the C4K footage at all?

Yes, that's the idea. Shoot in 4k so you have a 2x zoom in a 1080 timeline.

If you really have 4K DCI then it's 4096x2160 so this doesn't scale perfectly to HD. You need to crop or reposition frame.
If you have "normal" UHD 3840x2160 sources then this will scale fine and it's just a matter of setting in Image Scaling section and setting for Mismatched Resolution files. Default option should work in this case fine.

I shoot GH6 5.7K 60P Vlog and GH5S C4K. Neither are 16x9 I have my project scaling set to fit and thus get bars top and bottom. The zoom ratio to fit 16x9 is about 1.070 which then gives option to move image right or left too. Using inspector I set this zoom for these two tracks before converting to multicam clip. I leave it this way in multicam, just do cuts then flatten. Now I am back to the original resolution and I can zoom/pan etc to get the framing of each 1920x1080 clip in the timeline that I want. No quick way but the whole point for me is to use the extra resolution to frame after shooting. Can make a two camera shoot look like a lot of cameras with servo zoom too !!