Four fields are provided on the Case object that can be manually or programmatically set with quantities of hours.  When a Case is created, Case Flags will set the four fields with the values you specified in the Setup Wizard for the Custom Aging Speeds or with Account-specific hours if any have been set for that particular Account. You can create a Flow on Case which when run, will supersede the default and Account specific hours.

In the example given below, we will create a Flow to alter the escalation time for cases where the Priority has been set to High.This is just an example and should be evaluated before implementing into your production organization.

1. Navigate to Setup - Flows
2. Click on New Flow
3. Select Record-Triggered Flow and click Create
4. Select Case as the Object
5. Trigger the Flow when 'A record is created or updated'
6. For entry conditions, use Priority = High
7. Run the Flow 'Every time a record is updated and meets the condition requirements'
8. Optmize the Flow for Actions and Related Records

9. Click Done.
10. Click on the + button and add an Update Records element to the Flow.

11. Fill out the details for the element as follows:


The values for the fields are formulas for each Flag Age field. Here's one example:


12. Follow the step above for each Flag Age field.
13. Save and activate your Flow!