You need to select a target. You can use paper, a mat, or a box, to teach the dog where they should go.

I do this, using a post-it note. I start with it on the kitchen wall and hold a piece of food on it and tell the dog "touch". They'll put their nose on the target in getting the food. As they get the idea, I take the food off the target. When they touch, they get fed. If necessary, I'll point to the target or touch it with my finger when the food first leaves the target surface. Gradually, they learn to run across the room.

The turn and sit follows easily as they quickly learn to sit and wait for me to catch up with the treat. Then put the post-it on the baby gates, fences, etc. If you've used a touch stick for other training, it would translate quickly to this too. I prefer to not have the food out on the target once the dog has learned the touch command; I've watched too many dogs over the years go out in the ring and search for the missing food before turning to sit. With this method, the dog knows to sit and wait as I could be coming behind with the food. If not, jumping is fun too.

Teach the dog to run until they hear the SIT command. They're going to need something to run to. Another method is treating this as a retrieve. Put something like dowels out there for them to go to and retrieve, or send them to your place box. In the end, you're using a target again, just different kinds. Agility targets work well if the dog has learned them for contacts.

Do a gazillion go outs in a billion different locations.

They always need their target out there at least about every third time or the behavior starts to fade.