How to expand width of game after scale?

Phaser 3
1

Hey, I have a game which dimension is 1600x960 . When a user opens in any mobile device I want to FIT it first then expand only width. For example when I open the game in iPhone 6,7,8 plus it shows game at black area and red area is empty;

resize
resize.png795×506 4.23 KB

I set my scale mode like this;
scale: {
mode: Phaser.Scale.FIT,
autoCenter: Phaser.Scale.NO_CENTER,
},

Do you know what should I do next to expand only width for any device?