Just about every camera I have records in 4K, I record in full quality, and down convert when needed:
ffmpeg -i DJI_0029.MP4 -vf scale=1920:1080 -c:v libx264 -crf 35 DJI_0029-smaller.mp4
save this file to convert.sh and
chmod +x convert.sh
#!/bin/bash ffmpeg -i $1 -vf scale=1920:1080 -c:v libx264 -crf 35 $1-1080P.mp4
the output files will have a filename of filename.mp4.1080P.mp4, but for my use it's fine.