The formality distinction you are talking about is sometimes called the "T/V" distinction, because in a lot of the European languages that have a formality distinction in 2nd person singular pronouns have an informal singular with a "t" and a formal singular with a "v" (as many Romance and Slavic languages took the "v" form from the plural, and have similar roots for deriving the 2nd person pronouns). If you want to see a map of where there is a formality distinction, here you go https://wals.info/feature/45A#2/30.9/198.9. This map is of formality distinctions in general, not formality distinctions that derive from the plural.
The "v" forms in a lot of European languages derive from the 2nd person plural, but in many languages (such as Italian and German), the 3rd singular is the more formal form. In yet others, like Hindi or Hungarian, the 2nd person singular formal does not look like the informal or the plural. The European languages developed them after the fall of the Roman Empire, using the metaphors that PLURAL IS POWER (see also, the "royal we").
To browse a few more distinctions, see https://en.wikipedia.org/wiki/T%E2%80%93V_distinction#Table.
