Plastics are just like most car parts, in that they will need cleaning of dirt/grease/prior products and sometimes waxes/polishes.
If you are just looking to protect, Chem Guys New Look trim gel, AG bumper care, 303 Aerospace protectant, or a more permanent result with C4 from GTechniq (if they ever deliver your order...).
Ah the Joy of having them just down the road from me = Pick up, thank you please, Come again
AG bumper care is all you need really, pointless imo spending anymore money on a product for this area when AG is more than up to the task.