How do experienced professionals make domain switching happen?

A major chunk of my life I spent my time in OSS Telecom (Software Engineer) with my Undergrad and Masters tied to Network Communications, how do I pivot and gain expertise in other domains as life happens?

I am only at a lead big picture level because of the domain knowledge I possess in telecom.

If I were to go to Finance, Banking, retail, seeking advise on how to start from scratch and progress faster - would I lose my experienced SE status?