I like to use online calls mixed with pen and paper. I find this is the most effective way of learning online. I can screen share questions and then go over the working to make sure the fundamental ideas and problem solving skills are processed. This can be repeated until I am sure the student understands the idea and is happy to proceed. I would never ask a child to turn on a camera if they are uncomfortable with it but I usually will ask as it can help with sharing answers and working.
When I’ve been teaching my friends younger siblings in the past we usually do some practise together and then I let them try on their own. Then we come back and we go over their working. Depending on the age range of the child and the preference of the child (or parent!) I can change my level of involvement in the lesson.