Game wont go full screen on mobile

Can someone help me with the issue? So I’m testing .APK on mobile phone, but for some reason when I start game it wont go into full screen, there’s always side screen with black lines. I changed Maximum aspect ratio to 5 already inside project settings, also checked to use display cutout region and Enable Fullscreen Imersive on Kitkat and above, but nothing helped. Always having those side screen not going into the full.

I’m learning Android at the moment on template and this is where I’m stuck at the moment. Tried all advices on Google, but nothing seems to be helping. See picture below how it looks on phone.

I’m not sure if this is the right solution to your problem, but try unchecking the “Constrain Aspect Ratio” under the Camera Options section.