The Variant picker block shows buttons or dropdowns. Sold-out options stay visible and are crossed out.
To show color swatches, edit the product in Shopify admin, open the color option and connect it to a color metafield (for example Color from the product category). Each value then gets a color or image swatch. Swatches appear on the product page, on product cards and in collection filters.
Combined listings are supported: choosing an option that belongs to another product opens that product.