Hello @Gail6 thanks for your post, and welcome to the Square Seller Community...we're glad you're here! If you're asking if you can assign two different prices for the same item (depending on where it is available to sell), I don't think you can. You'd have to create two different items, with different prices, and then turn off/on website availablity (see next paragraph for details on that...)
When you create a new item, there is a section with options to include that item for sale on your website. If you leave this UNCHECKED it shouldn't be available on your website. As far as an entire category, you can test a new category, only adding those items you create with NO online availability, and see if this shows on your website. I don't think it will show up, unless you manually add that category to your website.
