In the field of protection, there are generally 4 groups of products: wax, sealant, hybrid and coatings. These products can be combined, but with mixed results. Knowing what the properties of a product are will clarify the end result.
Layering is the act of applying several layers of either the same product or different products. A popular example of layering is applying 2 coats of wax, or applying a sealant on top of a wax. Layering can be done with many different products.