You can now set all new Amazon EC2 instance launches in your account to use Instance Metadata Service Version 2 (IMDSv2) by default. IMDSv2 is an enhancement that requires session-oriented requests to add defense in depth against unauthorized metadata access. To set your instances to IMDSv2-only, you previously had to use the the IMDS Amazon Machine Image (AMI) property, set Instance Metadata Options during instance launch, or update instances after launch using the ModifyInstanceMetadataOptions API.
Source:: Amazon AWS