link. Also it is going to matter what state your peaches are from as to whether they are in season, late season etc. The box should say or the produce dept. personnel. If they don't you're shopping at the wrong place. Big joints like Costco could be getting peaches from lot's of places and you could be getting peaches that were picked early before being very ripe so that they have longer "transit/shelf life". If the peaches are stiff and not ripe you can ripen them more like in the second link for example. There are more ways on-line. It does also matter what variety you are buying and whether you just want a peach for cooking or for eating fresh. If you are canning peaches it's fine to have them be a bit firm because you're going to "cook" them anyway and they'll hold up to slicing perhaps a little better. Big store produce is many times a crap shoot at best. You can end up buying apples with almost no flavor, green beans that a blast furnace couldn't soften and on and on.
For example when you go to the big Kroger owned stores in Wisconsin my experience is that during apple season they will have big bins of 8 different kinds of apples but if you ask their produce people questions about which for eating, pie, sauce etc. all you get is a shoulder shrug. If you are stuck with just big stores for choices you might want to consider ordering from an on-line source. Shipping on this stuff has gotten to be more reliable. I'm sure some places will have a "sampler pack" of several varieties so you could experience some different levels of sweet, meatiness etc. I would check for places in South Carolina and Georgia because I know there are tons of roadside businesses and I'm sure many are doing on-line ordering/shipping. Try to use ones that are an actual orchard and not just a middleman.
https://www.butter-n-thyme.com/peach-season/#peach-producing-states
https://www.thespruceeats.com/how-to-ripen-peaches-2216828
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