Can we add "Specify the time criteria for this rule" other than 0min or 30 min like (12min,20 min).

Short answer: no - native Case Escalation Rules only let you pick 0 or 30 minutes for 'Age Over' (you enter the hours, then choose 0 or 30 from the dropdown). Custom values like 12 or 20 minutes are not possible there; it is a fixed platform limit. 

For minute-precise escalation, use one of these instead: 

1. Record-Triggered Flow with a Scheduled Path (easiest): add a scheduled path set to run, say, 12 or 20 minutes after your date/time field (or after the case is created / meets criteria), and put the escalation action - reassign to a queue, send an email, update a field - in that path. Scheduled paths accept any custom minute value. 

2. Entitlements + Milestones (the full SLA framework): 'Minutes to Complete Milestone' accepts any number, and Milestone Actions fire at exactly that time - ideal if you are tracking support SLAs. 

Go with the Flow scheduled path if you just need custom timing; use Milestones if you want a proper SLA model on Cases. 

If this helps, please mark it as the Best Answer so it helps the next person - thanks 🙂