Yes, there are a number of things you can adjust, some with a dial or lever, some involving changing the internal configuration.
The thing about Rayburns is that it's not necessarily repeatable. Depending on the weather conditions, the fuel, other factors, the way you set it yesterday may not give the same results today. So you learn, over time, how to adjust your Rayburn for the output you want in various conditions. It's very much trial and error at first, and will be again from time to time. I rather like that, but it might drive some people potty.
Adjustments on ours include a thermostat - how hot you want the water that's going into the tank and radiators; an air flow director that directs the hot air from the firebox to the boiler for the water or to the hot plate and oven; an airflow regulator that controls the air flow into the base of the fire and another that limits the air going up the chimney. The manual gives suggestions of settings as a start point, and tells you to experiment and find out what works for your system.