We have recently had a most challenging child at school: very, very bright, and struggling very hard to self-soothe during adjustments or transitions. Any transitions at all, including things that the child wanted to do, like get out his lunch and eat a cookie, caused crying.
What I have learned from this child: patience, empathy, respect for hard work, and also, when the child can be calm, it is his brain which does the most to help him. Not that a lap, or a hug, or a empathetic look or remark does not help him calm down, a lot. But, ultimately, it is when his mind is engaged, when he is intrigued or fascinated or curious or observant or amused, and his brain is working, that he is the most calm, during turbulent times.
This does not mean that we try to distract him with flashing lights and funny clowns, but calmly demonstrate something intriguing, and sit back. We model our own enjoyment, and invite.
There has been a lot for me to learn in watching this process unfold.