We design desktop and mobile screen in the same page and use the Custom Size setting to show our prototype (to overcome the fact that Figma can still not handle different devices for different flows…), the problem is that the Prototype option Fit Width is not available for some obscure reason. Therefore we MANUALLY add &scaling=scale-down-width to the URL to have it working and to have a proper link to share with client.
Would it be possible to just display it in the Option dropdown like for the Presentation setting?