Checkbox Size Xamarin Android

I've implemented checkboxes in my Xamarin Forms App using the following article:

https://alexdunn.org/2018/04/10/xamarin-tip-build-your-own-checkbox-in-xamarin-forms/

The only issue I have is that I can't set the size of Android, there is a question in the comments section, however there is no solution. No matter what I do the SizeRequest is always 64x64 - can anyone offer any suggestions or reason why I can't resize?