Whenever i develop UI, i choose a perticular device (some pixel…) and design accordingly but whenever i send it to testing, it comes out that items are mis-aligned, sized box for spacing looks good for this device, but doesn't work with another device, also font sizes also make a diffrence, small screen and a fixed font size is annoying. also for simple things such as Login page, i sometimes have to use SingleChildScrollView.

is there something like sp/dp like in xml (android) for flutter.

is there any way to make app adjust accordignly, i checked documentation but not satisfied with response.