You can add variants to a product that comes in more than one option, such as color or size. Each combination of options for a product that you sell is a variant of that product.
For example, you might sell a t-shirt with two options, such as size and color. The size option might have three size option values: small, medium, or large. The color option might have two color option values: blue or green. A variant from these options could be a small, blue t-shirt.
You can add variants on the Add a product page when you are creating a new product, or add or edit variants for an existing product at any time.
You can create up to 100 variants for a product. This limit can’t be raised for any account or plan. You can see how many variants a product has on the Products page of your Shopify admin, under the Inventory column:
Each product can have a maximum of three options, for example, size, color, and style. Options can be different from product to product. One product might use size, color, and style, and another might use weight, finish, and material. This limit of three options per product and 100 variants cannot be raised for any Shopify account or plan.
To sell a custom product that has more than three options or 100 variants, you need to edit your theme code.