Cessna 172 pilot reported had a sudden drop in engine power while in cruise. Pilot contacted ATC and was cleared through their airspace and continued to land at nearest airport.

Narrative

Upon departing ZZZ Airport; Aircraft X notified ZZZ Approach with a request for the VFR transition over the bridge with a Charlie Transition through ZZZ1 Airspace. The transition was approved and squawk code received. Approximately 6.6 NM north of ZZZ and 5.2 NM west of ZZZ2; Aircraft X had a sudden drop in engine power. The RPM drop went from 2350 to 2150. All instruments; flight control and engine control checks were made and found to be in proper normal operating position. Throttle power was added to determine and verify proper functionality. At this point; Aircraft X contacted ZZZ Approach with an immediate request for a right turn direct to ZZZ3. ZZZ Approach advised of the power loss and current flight status. ZZZ Approach cleared Aircraft X into class bravo airspace and to remain south and west of the freeway. Initial altitude assignment was given at or below 2000 ft. Aircraft X requested a 3000 ft and was granted. ZZZ continued to monitor Aircraft X progress. ZZZ contacted ZZZ4 on behalf of Aircraft X and was given clearance through their airspace. Aircraft X continued on to ZZZ5 with no further incident. Maintenance was notified and the aircraft was ground for further notice.