As I write this, I am on a iMac running macOS 10.13, but I am being told by Google Chrome that “to get future [] updates, you’ll need macOS 10.15 or later.”

Guess what, I can’t, my iMac is too old. It can only be upgraded to High Sierra (10.13). And can’t of beyond that.

Sorry, sometimes: Upgrades are forced over time.