Ours sometimes uses a sort of cartoon tone to play out emotional situations. In the past, they even used exaggerated facial expressions from cartoons, meaning posturing that people don’t typically use but are often seen in animation. They’ve also pretended to be different animals to express certain emotions.

It’s been helpful and heartening to read other responses.

Instead of expecting them to join you in your world, have you tried joining their world? Be a different character from the movie, talk to them as if they are the character they are acting.

Find ways to redirect truly dangerous behavior, of course, but otherwise this doesn't seem like a problem.

My 12 yo DS also does this and always has from a very young age. It's less frequent than it once was - but I also think of it as a stim. He gets absorbed in his stories and actually gets frustrated if he runs out of material to "make a story". I think of it as fan fiction - i guess? We've also encouraged him to write down or record his stories since he likes creating them so much - but he doesn't really want that. One thing that has helped us manage it when we are in different situations is to have him ask whether a certain place is a good place for him to make stories - and we also help identify what are good public places for story making and what aren't.

This sounds like delayed echolalia often called scripting. It’s not bad per say, very typical in younger children, until it starts to inhibit other activities and learning which you indicated it is doing. Cut back on or completely eliminate screen time and increase time spent doing structured hands on activities. You might also get him involved in theatre or reading and acting out plays at home. Seek out social skills groups and more interactive activities.

Any other kids do this with animals? Like feeling a need for a hug so they become a koala? Or angry so they're a lion? Or need to run so they're a dog or a horse?

At times it's cute and fun but at times it's inappropriate or dangerous. It's also confusing to friends who in 5th grade are outgrowing this kind of play.

My guess it's a coping strategy to anxiety or big feelings, but like you, OP, it can be worrisome when they don't snap back.

My DD does this and has from a very young age, with both books and movies. Acting out a movie is one of her favorite ways to relax and also I think she likes it as solo play (she's an only).

To be honest it doesn't bother me because often the alternative is very intensive curiosity, constant questions, monologuing at me. When she disappears into her world to act out a story, it can give me a break and some emotional distance, which sometimes I desperately need.

I have experienced her disappearing into this play acting when I want/need to talk to her about something serious, like when we've needed to discuss school behavior issues or talk through emotional regulation skills that she hasn't been using. That can be frustrating, but I recognize it as a defense mechanism and will usually drop it and raise it again later when maybe she is feeling more calm and less defensive. I have on occasion tried to weave the lesson into her playacting but she is pretty clever and aware and doesn't buy it.

We have been encouraging her to write and act out stories of her own -- we figure if this is something she's drawn to, it could become a creative outlet for expressing herself as she gets older, as well. She hasn't expressed much interest in her performing arts special at school but we might sign her up for a theater camp next year to see if she embraces it in that setting.

This sounds a lot like my son. I think of it as a stim. It happens at home to help him regulate and amp up. It happens out of home in times of high anxiety. I see him as using it as both a form of escape and as a form of control. My son tends towards super hero villains and especially likes to play out scenes of power. I’m not sure if this helps. I will say, maturity and predictability and medication has made it more like play most of the times these days. When he’s deep in, I communicate with the alter ego.

My elementary school-aged child is often in character from a favorite movie or show. At times they are scripting like echolalia but also full-body acting out a scene. I love this vibrant inner world and the joy it brings them but at times it feels like I can’t actually get through to them. It’s frustrating to feel like I’ve lost my child for an hour or even sometimes on and off a full day. A few times I’ve even found myself calling their name and saying “come back to me!” At times they even “act” dangerously, such as jumping up on a table or kicking someone because it was in the movie. We’ve told them that they are still them and the rules don’t change just because they are acting. I believe they only do this at home and not at school. Has anyone else experienced this? Would love any advice here!