Is there a good iOS Emulator for Mac with App Store access

I want to be able to download and run iOS apps on Mac OS to facilitate my research. Does anyone know the best way to do this? Is there an app around that anyone knows of that is particularly good at doing this?

Thank you for the help and apologies if there is an obvious answer. I can't remember being able to do this in Xcode and so far haven't found a great way, except possibly mirroring my screen.

Best, Alex