Mixed frame rate help?

Hello friends!

My wife and I shot some nice video on our last vacation to Europe using three cameras, Canon 5DMK3, DJI Mavic Air and iPhone 8 Plus. I want to edit the project and started one at 23.98 fps as that's what the 5D, Mavic, and most of the iPhone footage was shot at. However, there are some iPhone clips that were shot at 29.97 and some at 120 fps for slow motion. Since the bulk of the footage is at 23.98, I was assuming I'd edit in that. My question is that I noticed when I drop some of the 29.97 clips onto the timeline, they don't "look right." I then clicked "Automatic speed" and the clip slows down to 80% and looks normal. However, I'd like to play it at 100% speed, but have it look correct.

Questions:

1) Should I just drop the 29.97 footage onto the time-line and let FCP X handle it and hope it looks right on the final export?

2) Should I use compressor to transcode those clips to ProRes at 23.98 and then use those to edit?

3) Is there an easier way I don't know of?

I'm on the latest FCP X 10.4.6.

Thanks, community!
Daniel