How do I make a rug from strips of old jeans?

I would look into “braided rug” YT videos.

Check You Tube for rag rug making. People used to make rugs out of old clothes.

I made a door mat from the pocket of old jeans sewing the pockets onto a base, but you can easily sew a random patchwork of your old jeans - here's my how to for the pockets in case it helps https://vickymyerscreations.co.uk/tutorial-2/how-to-make-a-doormat-using-old-jeans/