also i need to know if the 2060 supports Nvidia resizable bar
Nope, I don't think so. Actually, NVIDIA announced that resizable-BAR support will be made available to GeForce RTX 30-series "Ampere" desktop graphics cards, notebooks that have RTX 30-series "Ampere" mobile GPUs, and future products.
The support requires not just a compatible graphics card, but also a motherboard that supports the feature. Most leading motherboard- and OEM desktop manufacturers began rolling out resizable-BAR support through UEFI firmware updates. Using the feature requires you to run your machine in native UEFI mode (with CSM disabled).
Edit: That was for resizable BAR. Nvidia Reflex is supported though. I should have been more clear.