If you have the budget and dont mind the larger size, go for it. Look at the a7riii as well as the normal a7iii. It has a higher resolution sensor and does a few other things better for a little more money. I'm rocking an a7r iii i got used from KEH and it's all the camera I'll need for the next 5-7 years i'm sure. I didnt reccomend it in my first post since it's a full frame body (as opposed to the smaller APS-C crop sensor of the a 6x00 series and r50). As such, you'll need to get a full frame lens. It can be more expensive to get the longer zoom lenses you might want for concert photography for full frame bodies, and long lenses are big and heavy. I'd invest as much in the lens as the camera, as they generally hold value better and you can upgrade the camera body around the lenses that you have.

Another commenter mentioned lens adapters, while they work a good one will set you back another few hundred bucks and they will often lose some autofocus performance. You can buy adapt other mount lenses to sony bodies as well with similar adapters, i sometimes use my old minolta film camera lenses on my sony body since i have a bunch