Hello,
By default, variable product attributes are presented as a dropdown in WooCommerce. WoodMart theme suggests the option to present the attributes as swatches. Swatches are available in text, color or image format. Swatches can be configured for global attributes only.
Please read and follow the instructions written in the Theme Documentation here that how to enable variations swatches for variable products: https://xtemos.com/docs/woodmart/variable-products-swatches/
Best Regards.