Apart from the personal devastation of being just a mere half-decade away from joining this particular user group, there is lots of good stuff in this piece by Bryan Kelly on writing for people over 50:

Designing for older adults isn’t about simplifying everything or creating a “senior version” of your digital experience. It’s about designing with respect, complexity, and care — just like you would for any other audience.

That's the gist of it, but Kelly also includes a range of research-backed personas to help you think about how different people might approach your content. Basically, it's 2026 and we are quite some way past the notion of the 'silver surfer'.