You can obtain information about EC2 instances using:

aws ec2 describe-instances

You can obtain information about specific EC2 instances using:

aws ec2 describe-instances --instance-ids ...

where ... contains one or more instance identifiers. For example:

aws ec2 describe-instances --instance-ids i-abcdefgh i-ijklmnop

The output of aws ec2 describe-instances uses pagination by default. If the response contains the key "NextToken" then you'll need to use that token to obtain the next page of information:

aws ec2 describe-instances --starting-token <token from previous response>