Force mobile app to have 16:9 aspect ratio

I would like to force my app to run in an 16:9 aspect ratio so that even my longer mobile can fit the game but I don´t really see an option somewhere to fix this. My question is how do I do that?

Found this thread: How to lock aspect ratio on full screen - Questions & Answers - Unity Discussions
Maybe that’s what you should do.
TL;DR: Go to Edit > Project Settings > Player > Supported Aspect Ratio > Legacy widescreen (1.86)