Some of the other posters have beaten me to it with the suggestion of a visual schedule.
It would be great to try these when you’re out at the park or shops too. In the park you could have a picture of the gate, the duck pond, a flowerbed, a swing, a goalpost, the gate, and home (or whatever distinguishable landmarks you can find in the order that you will see them). Refer to them as you go. “Here’s the gate. What’s next on our list?” And if he asks for home, refer to the list “we need to find the goal post, and the gate, and THEN we go home.” It’s crucial to follow through because it will help break the link between crying and getting to go home.
You can do the same at the shop. Trolley, clean hands, bananas, bread, milk, cereal, cash register, car, trolley, car, home. You do need to be disciplined not to squeeze in extra things on your list at least for the first few times.
The novelty will probably be great the first couple of times but he will eventually test the boundaries and it’s super important to be clear, kind and consistent. If he cries you can sympathise and cuddle, but return to the list and go through the steps.
It can feel cruel to force the issue but you are relieving him of a huge burden if you can break the connection between crying and getting mum/home. Imagine how exhausting it must be for him and it’s far too much control and responsibility for a two year old. Helping him to learn that the adults have it in hand, and he can relax safely, is what he needs.
I did this kind of thing with my ds before we knew he had autism and also used some of these techniques with my nt dd because they’re really great with any dc who can’t talk yet. It helps break things down into manageable and predictable steps.
I was also told that ds didn’t have asd at 2, but it turned out that what they really meant was that they didn’t have the diagnostic tools for that age. That’s not to say your ds is on the spectrum. But you can borrow techniques and see if they help.
Before ds was diagnosed I found these books really helpful
The Out of Sync Child
Raising your Spirited Child
Sensational Kids