Should I replace my 2x4GB RAM with 2x8GB?

Yes, swap them out for 2x8GB to get 16GB total, since you only have two slots and can’t add more sticks. That’s a noticeable upgrade for most daily use, multitasking, or light gaming. No need to go higher unless you know you need 32GB. Buy the capacity you want now and don’t plan on upgrading again until you replace the whole machine.