Here’s an interesting example where an expired domain was bought for $1k on Namejet at the end of July 2019.
All they did was upload French content to their site, even though most of the backlinks are in English.
And the site ranked at the top in France.
Screenshot attached. Most expired domains don’t go anywhere at all, but this one is an exception. Especially since the competition there is much lower than in the US. And these are mostly informational keywords, not commercial ones.
I didn’t find any hidden links, though they might exist.