I am creating app launcher icon for Android smartwatches.
What sizes should I consider while designing it? I tried searching for a template but I couldn't find any.
Downloadable UI guides are available for Android wear from the Android developer site. There's also loads of other information about design principles, structuring and a whole range of other thing in the "wear" section.
Apple also provide something similar for the Apple Watch if anyone is looking for that as well, It's called WatchKit. The downloadable design resources have all sorts of useful templates but you do need an Apple ID to get at them.