Mitama stan

Hi, I was wondering what method you have to use in order to make FEH widescreen like the attached images. I saw this in Nimi's stream and asked him how he did it, and he said that he forced FEH to use the max resolution it could. Is this something you can do on certain tablets or is it on emulators, etc? I know you probably can't do this on an iPad but if there's certain tablets like samsungs or whatever that can force max resolution, I'd like to invest in one.