reserve capacity for specific period

Your question is not properly clear but if you are talking about AWS EC2 then yes, it is possible to reserve capacity for your EC2 instances during specific times of the day using AWS Scheduled Reserved Instances.

To create a Scheduled Reserved Instance, you can use the AWS Management Console, AWS CLI, or AWS SDKs. When creating the reservation, you will need to specify the following information:

Instance type Availability zone Start and end time for the reservation Number of instances to reserve Instance tenancy (dedicated or default)

and read the AWS documentation for more details https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-capacity-reservations.html