Ec2 Savings Plan with Tags

Not possible with the way you are looking for as of now , however you can may be look into EC2 Instance Savings Plans if you have a segregation of instance families for your workloads between OD and SP.

Compute Savings Plans - These plans automatically apply to your EC2 instance usage, regardless of instance family (for example, m5, c5, etc.), instance sizes (for example, c5.large, c5.xlarge, etc.), Region (for example, us-east-1, us-east-2, etc.), operating system (for example, Windows, Linux, etc.), or tenancy (for example, Dedicated, default, Dedicated Host).

EC2 Instance Savings Plans - provide savings in exchange for a commitment to a specific instance family in a chosen AWS Region (for example, M5 in Virginia). These plans automatically apply to usage regardless of size (for example, m5.xlarge, m5.2xlarge, etc.), OS (for example, Windows, Linux, etc.), and tenancy (Host, Dedicated, Default) within the specified family in a Region.

Reference : https://docs.aws.amazon.com/savingsplans/latest/userguide/what-is-savings-plans.html