How to test an iPhone App application upgrade with only an iMac running xcode and simulator

I have an application that's been on the appstore for some years. It was developed completely on the iMac running xCode and tested on the associated simulator. This has worked ok so far, so I'm not interested in exploring the idea of acquiring a physical iPhone for testing.

I have now updated my app using the xCode IDE and tested that code in the simulator. I'm satisfied that a new user of the app would have no issues, but I would like to verify that an existing user would have a smooth upgrade experience.

I know that the simulator is unable to pull the existing app store version onto the simulated device.

My question is what are my options to get the released version running in the simulator so that I can test the upgrade process?

Apple is not my native language, so speak slowly and clearly. What I did a few years ago is get an iMac, load xCode, and replicated an Android application using Swift. So mostly just cookbook-level knowledge. I didn't purposefully save old files anywhere, but xCode has some kind of archive thing that I saw when I was moving code to the app store, and didn't know if I could somehow get one of those packages on the simulator. There is some kind of automatic backup thing that's been running...I just wouldn't know where to start. It looks like I've done "Source Control" > "Commit.." in the past, because it's only offering to update the files I've changed recently. I'm very scared of doing Source Control operations because I've had nightmarish results when fumbling around in that area without sufficient training. In my native tongue, I have more confidence, but here I can't even figure out how to see the history of commits.

So I think I need to revert, build, get that running on the simulator, then load the newest code into the IDE again, then load that on the simulator. But I didn't know if maybe there was a scheme that would let me load some automatically created previous compiled version that I'd placed into the app store.

I would seem that this is a common problem (testing an upgrade) except for the fact that I can't do it "the easy way", by downloading the released version from the app store.