It will not be the best option to just copy someone’s work and put it into your channel. It may cause a fatal issue to your channel. Unless you have permission to do so, the YouTube authority has the right to ban your channel permanently.
If you want to work on other people's videos, always check about the copyright acts first. To be honest, I may go with the common pattern of videos that will be completely shot by me. There are number of themes available to start with.
You can go with any of the food, cooking, prank, music, true story, film, daily experience, knowledge sharing, teaching, kids play, dance, painting, etc., or whatever you are having an extraordinary skill to show people.
Point to be noted, your video quality should be crisp with good sound quality. YouTube studio has a lot more functions to make your audio and video bold.