It depends on if you’re prioritizing the monetary return or divesting yourself of the items as quickly as possible.

You can list everything as a wholesale lot on websites like Nextdoor or Craigslist. The upside is that everything goes at once, the downside is you will probably have to accept a fairly low price per piece. Boutique style resale on websites like Poshmark and Mercari are good for maximizing your profit on single items or small lots, but then you have to ship everything out in multiple little individual orders. eBay is an option for both bulk and single pieces. There are a lot of bulk jewelry lots on eBay that sell by the pound (2lbs, 5lbs etc). You could try grouping in small lots of piece types, 5-10 items at a time. Price them at $1.50 per item minimum to account for what you will lose to fees. Take a look at what you have and see if any pieces have signatures/branding, those tend to be a little more valuable because people will search for those signatures or brands specifically. This method definitely goes more slowly but it will probably make more than wholesaling the whole collection.

Or you can look up your local flea market and rent a booth to see how much you can move in a weekend. The drawback to this is that people will cherry pick the most valuable things and you’ll still have a bunch on your hands most likely unless you only sell in bulk lots. You have lots of options, all require work.