Here are some simple yet effective calming strategies to help your kids regulate when overwhelmed:

Music Playing gentle music is soothing and allows the brain to fall back into a gentle pattern.
Other Sounds Waterfalls, soft drumming, nature sounds – try finding them on YouTube.
Lighting Soft lighting – fairy or dimmable night lights.
Mindful Colouring or reading.
Connect with Nature Go for a walk, create a treasure hunt and collect different objects you find or play a game of ISpy.
A mindful walk Listening to the sounds around you, looking at colours, taking in the different smells.
Playing with balloons Keep the balloon off the ground but have them move slowly and gently.
Texture bag Place several small objects in a bag. Have your child reach in and touch an object, one at a time, and describe what they are touching.