@martins removed their quoted postThe answer to the the question asked is in the FAQ #ratingcalc.
For the first 20 games
"This rating is calculated as the average of all the games you have played. Each game is scored as being your opponent's rating (for a draw), your opponent's rating plus 400 (for a win), or your opponent's rating minus 400 (for a loss).
Thus we can see that if a provisional player wins their first 5 games against players rated around 1200 their rating will be around 1600 as a function of the mathematics and not amazing at all!