Assuming a poor diet with large calorie surplus over your base metabolic rate for a regular non-exercising day? It’d take a lot of cardio to offset that. Usually about 3,500cal worth to shed a pound of fat. If you were eating at your regular BMR consistently, you could do 500cal of cardio per day to loose a pound a week. Most folks choose to create the weekly deficit with a combo of eating several hundred calories a day below BMR and combining that with intentional exercise, as opposed to just relying on one method.
In my opinion and experience, it’s optimal to use strength training as a large component of your exercise, combined with shifting to a diet that is slightly below BMR in calories but heavily made up of protein. This allows the body to retain and even increase skeletal muscle while losing weight, so that most of the weight shed is fat, not a mix of fat and muscle. Think “lose fat” not “lose weight”. Again, this is optimal but not doable for some.
