How can the durability of resin models be improved (sold ones) ?

Many companies sell resin models. The details are always very crisp, but durability often leaves something to be desired. They are often not very resistant to impact and bending. And when they break... they are very difficult to repair permanently!

Do you have any tips for improving the durability of resin models? Perhaps applying an enamel varnish or just a varnish? A specific latex primer (no idea if that exists) or something else?

To be clear, we are talking about models that are sold, not models that can be 3D printed :)