Absolutely. It's fully documented on GitHub, by the way the usage is very simple.
A bool property called HasAccessibilityFontsEnabled returns whether these are set on the device.
bool isEnabled = CrossDeviceFontSize.Current.HasAccessibilityFontsEnabled;
The DeviceFontSize property returns the actual font size set on the device:
SystemFontSize currentFontSize = CrossDeviceFontSize.Current.DeviceFontSize;
The returned value is of type SystemFontSize, an enumeration described as follows:
public enum SystemFontSize
{
ExtraSmall,
Small,
Medium,
Normal,
Large,
ExtraLarge,
Huge
}
At the moment UWP is not supported.