Hi Olichar,
Congratulations on your new mattress … you certainly made a high quality choice :).
There will be a break in and adjustment period with any new mattress for the first few weeks so I would give things a little more time before considering any changes or adding a topper but there are some suggestions in post #2 here that may be helpful.
Pressure relief and support are mainly opposites because when you make a mattress softer you generally increase pressure relief but also reduce the support under the heavier parts of the body so changing one changes the other in the opposite direction. The goal with any mattress is good alignment though so to some degree it will depend on whether you are referring to primary support (under the heavier parts of the body) or secondary support (under the more recessed parts of the body) because there are different support needs under different parts of the body. There is more about primary and secondary support and their relationship to pressure relief in post #4 here and in post #2 here.
While I would wait for a little while yet before making any changes … if you do decide to add a topper then post #2 here and the topper guidelines that it links to can help you choose the type, thickness, and firmness of a topper that will have the best chance of success and the least “risk” of exchanging a pressure relief issue with an alignment issue.
Phoenix