This is definitely on my mind as I consider whether (approaching my half-century) I can switch careers at all, without going back into a full-time role.

Freelance word-of-mouth has a habit of drying up in difficult times (like the times we've been through), and at any rate it is rarely useful when you want to significantly switch direction; those mouths likely have far less interest in the new words.

There is, to some extent, a way forward, which is that you do a chunk of your primary promotion mutually. That is, find someone else you are working with a lot, or multiple someones if you are organised, whose work you respect, and agree a simple, mutual cross-promotional scheme that you can both monitor.

Or agree to swap writing biographies, marketing blurbs, all the things you find difficult about writing about yourself.