guiScale

Key	Type	Default Value
guiScale	Int	3

The guiScale setting is used to set the GUI scale of the game. The GUI scale is the size of the game's user interface. The default value is 3.

This setting translates to the guiScale setting in the options.txt file.

build.gradle.kts

modSettings {
    clientOptions {
        guiScale = 3
    }
}