Create different rule groups organized by the specific nets you are targeting. To create custom rule group folders, right-click rules in the Project Explorer under Rules and Results, then select New Group.
Then simply copy and paste (right-click >> copy) the specific DRC you want to have in both rule groups. In this case, copy/paste the Diff Impedance Rule to each Rule Group folder you have created. Here, I have the Diff Impedance DRC in both the DDR_Diff_Pair rule group and the PCIe rule group.
Then, simply click on each respective Diff Impedance DRC and change the Parameters to target the specific impedance value per your spec for those specific nets (in this case, DDR nets impedance target vs PCIe nets impedance target).