Amazon Aurora now supports T3 and R5 instance types in AWS GovCloud (US) Regions

Amazon Aurora now supports T3.large and medium instances as well as R5 class instances in AWS GovCloud (US) Regions. Using T3.large instances with Amazon Aurora is a cost-effective option for smaller workloads such as test, development, and QA, while still giving you the option to use larger class instances for production deployments. 

Source:: Amazon AWS