THE ACOLYTE creator Leslye Headland confirms The Stranger was intended to be the first Knight of Ren.
βIt was in the design of the character, as well as knowing that we were going to introduce Darth Plagueis, who has to end up with Palpatine as his apprentice. Following the Rule of Two β a precept that limited the Sith to just two at any given time, a master and an apprentice β one way to keep it going is if the Stranger is the first knight of Ren, part of a Sith-adjacent culture that we know eventually survives.β
(Source: The Art of The Acolyte)