Would you like to do what i have been doing - i have been using a good 19 to 24 inch long duffle bag or gym bag with a single shoulder strap to carry about 2 changes of clothes and coat and outerwear, and a good school backpack for everything else?
Would you like to use the backpack to carry both clothes and other items? Are you looking for something like a suitcase but with 2 shoulder straps and no wheels?
I have used jansport backpacks in my adult life as carry-on luggage. They are not the most heavy duty backpacks. They are lighter weight than other bags, they can work ok if you don't stuff the bag too full or pack in a huge amount of weight. My last jansport ripped along a seam on a trip to central Europe in 2023, but it was probably my fault for over-stuffing it. My current backpack that i use for whatever is not clothes is a quechua backpack that I bought at an outdoor and camping store in Munich, Germany. I like that it has better padding on the back than the Jansports but I am not necessarily satisfied with it because it doesn't fit under the seat on planes and the back panel is too rigid so the bag can be flattened when empty but not folded when empty.
How much padding do you want against your back?
Unfortunately I have wasted money on the the kind of low-end day-backpacks that can be folded up and put into a little pouch. They are pieces of crap that can't handle the weight of a quart-sized bottle full of water. A small jansport backpack would work good as a day backpack and could probably be stuffed into your bigger bag without difficulty.
Edit: I checked the tag. The specific backback model I bought to replace my Jansport is the Quechua NH Arpenaz 300, 30L . It is supposed to be about 1,830 cubic inches. It isn't the worst or best backpack. It is meant for hiking. You should just buy one of the backpacks you saw on Amazon.