Based on their degree of control and influence on projects, there are 3 PMO Types - Supportive PMO, Controlling PMO, Directive PMO. Gartner classification has 4 types.
Types of PMO — MIGSO-PCUBED
Different Types of PMOs - PMO 101
Project Management Articles - Page 3 of 4 - PM Vidya
Michael Vidyakin: Introduction to PMO (UA)
Are the 3 types of PMOs, according to the PMI´s perspective, still valid for the challenges organizations face in the 21st century?
PMO (Project Management Office): Definition, Meaning, Structure & Roles
Are the 3 types of PMOs, according to the PMI´s perspective, still valid for the challenges organizations face in the 21st century?
What is the role of an IAS officer in PMO? - Quora
PMO Types - Supportive, Controlling, Directive - PM Vidya
Are the 3 types of PMOs, according to the PMI´s perspective, still valid for the challenges organizations face in the 21st century?