An example development path for a future Product Owner:

Agile basics - introduction to agility
How to work in Scrum - introduction and process simulation
The use of IT tools in managing team work (Jira, Trello, Miro)
Product Owner's work tools
Working with requirements in an agile approach
Evidence Based Management, or how to work with metrics
Introduction to the Lean Startup concept
Design Thinking - Innovation based on understanding user needs
Objectives and Key Results (OKR) method as a way to precisely manage the organization's strategy and goals (accredited training)

Check out other training and development paths

All training
For the manager/leader
For the scrum master