Screenshots for app store review

How can we generate screenshots for all devices to submit the app for review?

The app does not run on a simulator and is device only. I only have an iPhone7 and am unable to create screenshots for 5.5" and 6.5" displays, which the Appstore connect console is asking for.
Device-specific screenshots can be captured in Simulator for each simulated device as described in the Simulator Help:

https://help.apple.com/simulator/mac/11.0/index.html?localePath=en.lproj#/devdefc2debe

Simulator is installed as part of our Xcode tools and enables you to install your app using a few different methods. If an issue is preventing you from viewing your app in Simulator - or you are unsure how to run your app in Simulator - we recommend viewing the resources below:

Run an app on a simulated device
Troubleshoot Simulator

Additionally, more information about our screenshots requirements can be found in the Add App Icon, App Previews And Screenshots section of our App Store Connect Help.
If you rely on a third party library (whose architecture is outside your control) which prevents it from running in the simulator, you could try making a backup of your project, then carving out the smallest portion of the app which prevents it from working on the simulator then provide the Simulator's screenshots of your app. Perhaps the newly announced App Clips might help break it into runnable chunks in the simulator?
Screenshots for app store review
 
 
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