Which resolution should I use for my in-game screenshots in the App Store?

In App Store Connect I can add up to 10 images for each iPhone/iPad display. But I don't know which resolution is the best for my screenshots in the App Store and I don't know if the screenshots could be displayed distorted if I don't upload png images for each iPhone/iPad display in App Store Connect. Should I upload for each iPhone/iPad display up to 10 screenshots in the highest possible resolution? For example, for the iPhone 6.5" display it would be 1284 × 2778px or 2778 × 1284px.

Which resolution should I use for my in-game screenshots in the App Store?
 
 
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