Variant selectors look simple, but they have a big impact on product page usability. The two most common patterns are dropdowns and swatches.
Dropdowns are useful when the option list is long, technical, or not visually meaningful. They keep the page compact and work well for sizes, plans, formats, and configuration options.
Swatches are better when the customer benefits from seeing the option quickly. Colours, materials, finishes, and simple size buttons can all work well as swatches.
The problem is using one pattern for everything. A colour dropdown can feel slower than it needs to. A huge grid of swatches can feel messy and difficult to scan.
In ID_within, I use both patterns so the product template can be tested in different scenarios. The theme needs to handle selected states, sold-out variants, price changes, compare-at prices, and add-to-cart availability no matter which selector style is used.
Good variant UX should make the decision easier, not just make the page look more advanced.