Most exercises don't required much space at all. This is aside from running and distance physical activity of course. If you are able to find a space where you can comfortable lie on your back fully stretched out, that area should be enough for you to do a lot of exercises. There are a lot of apps on playstore that offer effective workouts without needing much space or equipment. If you search up "Leap Fitness Group" on playstore, you can find all of their fitness apps that mainly use body weight exercises to give you a good workout.
Yes of course I love to exercise in my room and all I need is about the space that a yoga mat takes up, stretches and yoga counts as exercise it doesn’t always have to be cardio to be counted and even small weights can be used in small spaces I hope this helps and good luck