Are you on Chess.com ? If so when you joined you would have been offered an ability level choice , mine was beginner , intermediate or advanced . Your initial rating on all time controls ( I think ) would then be set by that choice . I chose beginner , which gave me an initial rating of 800. Other levels , I’m not sure . After you’ve played games on Chess.com your rating would be adjusted every time depending on whether you win ,lose or draw . Not sure about other platforms . Know of some people who were offered the initial option of ” new to chess ” which would start you at 400 , I believe . Hope this helps 😄