I trained Simba to come without a leash indoors to start. I started with having her sit and stay. At first, I could only take one step back before she tried to follow. Before she would get up I would say come and point to my feet. She would get a small treat. As she got better, I took more steps back and finally walking around the corner of a wall. Taking it outside, we started on a long leash. I paired a whistle with the command come in case in the future she’d be on the other side of the field and couldn’t hear me. As she walked away from me on leash, I would blow the whistle lightly and said come as I pointed to my feat. She would return to me and get a treat. After much practice where she returned every time, we started our practice off leash. A mistake I made was not adding distractions during the trading like the following video does. A couple of times she took after a bunny but it would take more than a couple of minutes with several whistle blows to tame her desire of the hunt, remember her training and return to me. You need to be consistent with the training. It’s time consuming at first but the payoff is great. Good luck.