https://www.politico.eu/article/queen-elizabeth-death-plan-b...
Is there another monarch alive with this many subjects?
If you start counting what we'd usually call dictators, there definitely are bigger ones. The monarch/dictator line gets a little blurry and subjective/political I believe.
Given that all the countries with more population than that have a constitution and not a sovereign, it's safe to say yesterday she was the most prolific monarch alive.