The general separation exception requires you to leave service during or after the calendar year you turn 55. Leaving at 54 and withdrawing at 56 does not satisfy that rule.
A qualified public-safety employee can use the earlier of age 50 or 25 years of service under the plan, after separation. This tool screens qualified-public-safety status and service separately; it does not determine whether your position qualifies.
These exceptions belong to employer plans. Rolling money to an IRA before a later distribution can remove the separation-based exception, even though another IRA exception might apply.