8 years at major tech company - looking for help/advice on knowing when/whether to switch

I’m in my late 30s and have spent the last 8 years at a major tech firm going from an individual contributor to a director. I’ve never worked anywhere else in my career. I’m having a really hard time figuring out if/when it makes sense to switch companies. I’ve been experiencing some burnout and feeling really unsettled as to whether this is the company I want to be at for the next 8 years in my career. I’ve never had to interview before and the thought of it is a bit overwhelming. How do other people make this decision?