Unless the product containing the sealant says to, then no. In most cases, wax after sealant is unnecessary.
The reason you should not use wax after using a sealant is that the two products have been formulated for opposing purposes.
Waxes are meant to provide strong protection from UV rays and environmental elements such as acid rain and tree sap. Sealants are formulated to remain on top of a surface so it can bond with paint, which makes them ideal for metallic surfaces – especially if your car's paint has a high metallic content – where they won't discolor or change appearance over time."
And as long as your clear coat/paint isn't wearing out (rubs off easily) there should be no need to use any kind of clear coat.
In summary, using both sealants like Underbody Seal by Schutz and wax is mostly unnecessary, especially on a budget. And if you use wax after using sealant it will only last about 3-5 months at best.