If I upgrade my Mac, will it be powerful enough to edit with Premiere Pro?

In addition to all of the responses, all 2011 iMacs are now in "Vintage worldwide" support status at Apple itself. That means that if a hardware component fails, then officially it can only be repaired at select authorized service centers in the US and Turkey, and that hardware availability is limited.

What's worse, none of the discrete GPUs that were available at all on any 2011 iMac has enough discrete or dedicated VRAM to properly run any newer version of Premiere Pro: The program will run, but the renderer will be permanently locked to the software-only mode, and your system may experience crashes while running Premiere Pro.

And before you rush out and buy a newer Mac of any type, keep in mind that Apple is phasing out the use of Intel CPUs and the x86-64 platform in favor of Apple's own ARM-based CPU platform and architecture. In fact, the first such platforms are now beginning to be shipped to Apple stores and authorized resellers, in the form of the new late-2020 MacBook Air and some versions of the new late-2020 13-inch MacBook Pro. These newer ARM-based Macs are not yet certified compatible with Premiere Pro.

Increasing the RAM is going to allow your Mac to better function as an editing platform but there's a lot of functions in your IMAC will remain the same and will be old enough for the new updates for example the graphics card,cooling system etc.

it's not an easy or cheap process to upgrade your IMAC and make it faster for editing so i would suggest also like peru to save your money for a newer IMAC.

I don't know if this will help with deciding about a Mac, but here are some things to read https://community.adobe.com/t5/video-hardware/premiere-pro-hardware-articles-to-read-before-you-buy-or-build/m-p/11557686

I've moved this to the Video Hardware forum.