You can assign SLA Policies directly to tickets. Any agent that has ticket_sla_admin WordPress security capability can directly change the SLA profile on the ticket. But, it is much more useful to assign SLA Policies to the taxonomies that are used on the ticket. This allows the ticket to automatically be updated with a policy and the due date calculated at the time it is created.
You can assign SLA policies to:
Simply go to each of those screens and find the SLA ID field select the policy from the drop-down.
For example, to assign an SLA policy to ticket PRIORITIES:
Now, if a ticket is received with that priority, the SLA is automatically assigned to the ticket and a due date calculated.