It is clearly listed on AWS Instance Types [1]

Each vCPU is a thread of either an Intel Xeon core or an AMD EPYC core, except for M6g instances, A1 instances, T2 instances, and m3.medium.

Each vCPU on M6g instances is a core of the AWS Graviton2 processor.

Each vCPU on A1 instances is a core of an AWS Graviton Processor.

[1] https://aws.amazon.com/ec2/instance-types/