Hey, @MandyRenee56 !
Ash here from the Shopify team. Thank you for posting your question in the Shopify Community Forums!
There are a couple ways to make bulk edits to products and variants in your store. I’ll provide some details on each method below for you to check out. The first option is using the Bulk Product Editor, which is built into the Shopify Admin. This editor allows you to make changes to existing products and variants in your store in bulk, eliminating the need to open each specific product page. We have some more information on using the Bulk Product Editor over here in the Help Center. While this tool is a great solution for editing existing products and variants, it sounds like you want to add some new variants to existing products, and so I believe the second method will be better suited to your needs.
The second method is via CSV file. You’re able to export the products in your store to a CSV file, make changes to that file in a spreadsheet program like Excel or Google Sheets, and then re-import it into your store to update your products. When using this method, I suggest exporting your products twice and saving an unedited export of your product list as a backup. The Shopify Help Center has a bunch more information on using CSV files to export and import products you can check out!
Let me know what you think of these solutions by replying here. Happy editing!