Convet MOV files to MP4 in OS Sonoma 14.1.2

Modern MOV files are MP4 compatible. Simply renaming would do, if you prefer to see .mp4.

Legacy MOV files may need to be converted since far before Sonoma. HandBrake is a powerful tool for such conversions. It takes just about any format for input, and can output to .mp4 (or .mkv), using manual settings or with handy presets.

There is no need to convert .mov to .mp4 unless the video or audio codec needs it to make it compatible with QuickTime Player. Another approach is to use IINA which plays almost any codec.