Only if the ageism is on favor of the younger person. It is never illegal ageism to always hire the oldest candidate.

Every ageist situation that I have encountered thus far (am age 46) was "not a cultural fit."

I look younger than I am, but my patience for over-working too many hours is at an end. Years of stress have led to health issues that have to be managed.

But this all rolls into "not a cultural fit."

Yeah, and as a worker in his 20s who prioritizes work-life-balance, I wouldn't be a culture fit at those places either.