Yes, escalation is a feature of these types of offenders. It's quite a few years ago now, but in our last house, the neighbour opposite kept exposing himself to my wife.
I asked neighbours - she was too embarrassed and stressed to want to do anything. There were a load who had been subjected to the same thing. In the end, four women, including my wife, reported him and he turned out to be a serial offender.
They all gave mutual moral support to one another, none would have complained alone, so it's well worth joining forces.