Does sleep training work if implemented after 1 or 2 years?

JKR

Any EBF mother here who co slept till at least 1 or 2 years and started sleep training after that (teaching baby to fall asleep on their own after a bedtime ritual, fall back asleep on their own if they wake up in between, and be able to sleep alone in a room?) Was it a success or failure? Which method was used? Or is that too late for anything to work?