My son started having tantrums when he didn't get his way and would throw objects across the room like even as far as trying to throw the table. I learned that counting to ten and telling him everything was ok really helped.

When my son gets angry he’ll spew out nonsensical excerpts that aren’t related to the situation. My husband and I redirect him and remind him that saying nonsensical things is kinda wild. Sometimes the things he says are kinda funny, and I understand. I guess the alternative, attacking or punching a hole in the wall? Boy, I am I glad I curbed his aggressive, physical tendencies, he could probably do a lot of damage.
I would try to help him channel his anger to something physical, like a punching bag. Breathing is also good, counting to 10 slowly. If he has hobbies, have him use that, example, drawing.

How wonderful he’s had the same social worker for so many years!

Thanks @A MyAutismTeam Member - how old is your son? Does his therapy team allow that if he gets frustrated with an activity they are working on? My son was getting super ticked with an activity, and the therapist wanted him to tell her no or all done (first to encourage him to communicate, but also so he doesnt think getting upset is how he gets his needs or wishes met), but he went so far past annoyed that he was clearly blocking out anything she was saying. I joined the activity to try to help soothe him. He finally said no and she shut down the activity, and he calmed down. It was so difficult to see him so frustrated!