Theoretically, they could scale out the Chess ratings such that all ratings and rating differences are multiplied by some factor. With some manipulation, chess would become the deepest game. According to your definition of deep.
I'm guessing a bit here, I'm not 100% sure how the rating calculation works.
A goal of game design is depth. Depth can be defined as the difference in rating between the world champion and an average player. Depth in Elo:
Go 3260
Shoji 2200
Chinese chess 1980
Chess 1630
Checkers 1240
Stratego 860
Tic Tac Toe 0
A goal of game design is naturalness. Soccer rules are simple and football rules are complex.
Chessmaster Edward Lasker:
"While the Baroque rules of Chess could only have been created by humans, the
rules of Go are so elegant, organic, and rigorously logical that if intelligent
life forms exist elsewhere in the universe, they almost certainly play Go."
What are the deepest games?
What makes a game deep?
What are the most natural pieces for fairy chess?
What kinds of pieces promote depth?
I wrote an analysis at https://jaymaron.com/vikingchess.htmlMathematics of Elo ratings: https://jaymaron.com/sports.html#gamedepth