I want to build a rocket stoveoven for cooking.
I was wondering is there a way to control the temperature and if there's something I need to take into consideration in the design in order to do that?
For baking, you will need the oven chamber to have some mass so the temperature doesn't fluctuate all the time as the fire changes. A few inches of heavy, sandy cob all around the oven chamber, with insulation around that, is likely to work.
Overall temperature control is probably something you will have to get used to controlling by fuel feeding rate. An oven thermometer of some sort would probably make this considerably easier, especially if you can get a remote reading one, like one that sticks through the wall. Keep it out of the direct flow path from the firebox so it reads the average internal temperature.