One retail establishment I have found is Torrid for rings and bracelets, up to a size 11, and some that are split so that you can adjust to fit even larger digits. I have the problem of fingers that are two different sizes, the first two ‘pointers’ are all 4 a size 10, while the outside 2 on each hand are size 9’s.
For necklaces, try looking at Hobby Lobby or Michael’s in their home made jewelry sections. They have a lot of styles of necklace extender chains and such, plus parts to repair or replace clasps and connector loops and various other items. You can also find almost any style of charms/beads and things to add to your necklaces. I have also found adapters to convert pierced earrings to clip-on at both places as well as on Amazon. All you need to work on your jewelry is a couple of pair of long/needle nose plyers.
Don’t forget a bench vise and arc welder and air impact system to make sure you get it all put together to stay, LOL. Look around, jewelry is an easy project to learn to keep your favorites ready to wear for as long as you want them, just like a little sewing will keep your wardrobe in the right condition and not cause a donation or worse, tossing it out. Heaven forbid.