XGBClassifier: make the output of predict_proba ascending regarding a specific feature
You can enforce such monotonicity with the monotone_constraints (hyper)parameter:

https://xgboost.readthedocs.io/en/latest/tutorials/monotonic.html
https://stackoverflow.com/questions/43076451/how-to-enforce-monotonic-constraints-in-xgboost-with-scikitlearn