Is there a way to display multiple images in exactly 3 or 4 splits on one screen?
We recommend using the video collage added in version 17.
Other methods require calculations or zoom in to match visually.
A maximum of 25 clips, 1 to 5 vertically and 1 to 5 horizontally, can be arranged.
You can also set the spacing between clips and roundness.
It's in OpenFX's filters.
Compared to other filter functions, it requires a little special settings, so you won't be able to use it until you understand how to use it.
The following video is very helpful.
There is also an official instructional video. The video is 1 hour and 16 minutes in total, but the video collage is 30 minutes from the beginning of the video.