The inbuilt editor allows you to cut the clips right there on the conversion screen. You can choose between MP3 and AAC as the output and adjust the bitrate of the audio. I would gladly convert all the videos to audio to save some space on the phone. There are plenty of apps that can convert videos but most of the space on the phone is occupied with music videos which I never watch. The first app in the list lets you convert video to audio.
The app is built upon the FFmpeg library which is used by many popular video converters in this list. Timbre is not just a video and audio converter, but it also a somewhat video editor – can cut and join two videos.
Video Transcoder is a free and open-source app, which means it will not show you intrusive ads, neither you have to worry about your privacy. While there is no shortage of video converters for Android on the Google play store, most of them are filled with sketchy ads or have a limit to the number of videos you can convert.