Ive tried multiple online tools to resize my screenshots for the 4.7-inch and 5.5-inch formats at 1334 x 750 and 2208 x 1242 respectively. For some reason the largest I am able to get my screenshots is 1136 x 640? That is the original size of the screenshot I am using. Is there any way to modify the image and make them larger than the original to have them fit the appropriate settings?
Install the app on those devices and take the screen shots. If you don't have those
devices, load your app in xCode and run it in the appropriate simulator for each
size and take the screen shots. Up sampling an image is never a good idea but
if you absolutely must do this, any decent graphics editor, even preview can perform
this change with ease.