[busterarm]

Start embedding links in the text of your old content that point to your new content (when contextually appropriate, of course). Not as warnings, but if for some reason you mention a topic or word that's relevant to a newer article...

[macintux]

Which reminds me, I was really impressed with Justin O'Beirne's blogs on Apple & Google maps, specifically that older blog posts are explicitly flagged as being no longer accurate.

And his design is so clean that the flags are obvious without being obnoxious.

https://www.justinobeirne.com/cartography-comparison

[alphadevx]

Thanks for the tip, will try that where appropriate content relationships exist, but suspect it's minor occurrences (when you blog for 20+ years, your output varies considerably in terms of topics over time!).

Google does not like my new topics it seems, starting around 2012, but thankfully unlike the OP who I have a lot of sympathy for, my blog is for fun and not livelihood.

We write for bots, so they can decide to share with our fellow humans (or not), such is our lot...

[busterarm]

Depending on your blog software, you might be able to automate it. ;)

Seems like something a Jekyll or Hugo plugin could do quite well.