Hi Darla, you can create a "patch" from another old pair of jeans. Cut a square piece from the old jeans that is larger than the hole of the ones you want to repair. Place it inside the jeans you're repairing and use iron on tape between the two. Or you can make a decorative patch to go over the hole at the knee. You could create a few others so it looks intentional. There are also fabric glues available that will last through several washings. Here's an article with good advice. https://www.manmadediy.com/2651-the-diy-tailor-an-easy-way-to-fix-holes-in-your-jeans-and-other-garments
WalMar3t and ther stores sell jean patches that iron on the inside of the jeans.
Take an old pillowcase or interesting scrap of fabric. Cut out a flower or whatever you like, iron interfacing to it, and whipstitch over the hole. I used a sixties pillowcase with psychedelic flowers to fix my granddaughters jeans, and it became her favorite pair
do a search on Pinterest for mending jeans. There are some really cute ideas there. 😉