Product variants can be very useful, even essential for certain types of products. However, we recommend that you use them sparingly. Indeed, offering too many options can quickly make your product page too full and therefore the decision-making process of your clients too complicated.

Let's take the example of the skirt again. Offering two options (colors and sizes) seems coherent, the client understands very quickly that different colors are offered, and the choice of the size seems obvious in the context of selling clothing.
On the other hand, if this model of skirt also existed in different materials, we should have included an additional option called "MATERIAL" with the variants "LEATHER", "TULLE" and "SILK". This would have greatly increased the choice of options for our clients.
Although this way of presenting things is possible, it’s not the most intuitive for the clients, nor the most effective for our products.
In this case, we recommend splitting this skirt model into 3 products: a tulle skirt, a leather skirt and a silk skirt. 

That way, these three major options would be present in the product list, and more visible for the clients.

Moreover, the keywords "silk", "tulle", and "leather" can represent good opportunities to drive traffic on your Shopping app. Each material variation would have its own product page, its own title, its own tags... So many opportunities to highlight your product.
As you can see, here again, everything depends on the type of product you want to sell. The way you present your product must be carefully thought out and you must take into account both the user experience for your clients and also marketing to maximize your sales.