/setmaxplayers command not working after transferring world from realm

Me and my friends have recently been working hard on making a hunger games map and since we are about half way done I decided to transfer the realm we have been on back into a normal world. But then I ran into the issue of the /setmaxplayers command not showing up. We had originally planned to have the map max out at 16 people but without the command we can only have 8 in the server at a time. I should mention we are on Xbox and if anyone could get back on how to solve this that would be good.