ffmpeg install and use to reduce/compress video size

Installing free https://www.ffmpeg.org/ (download the source code)
reducing a mp4 video file size. Command used to reduce a video file size without loosing quality your output file size will always depend on the complexity of the video image (details, movements, colors, etc)
ffmpeg -i originalvideofile.mp4 -c:v libx265 -c:a copy -crf 25 reducedsizevideofile.mp4
The 25 is output quality lower than 25 better quality. You can use other parameter/commands s to compress a video file.
Try these other commands
ffmpeg -i input.mp4 -s 1280x720 -acodec copy -y output.mp4
ffmpeg -i input.mp4 -vcodec h264 -acodec mp2 output.mp4
ffmpeg -i input.mp4 -vcodec h264 -b:v 700k -acodec mp3 output.mp4
List of ffmpeg codecs https://ffmpeg.org/ffmpeg-codecs.html