Co-Regulation: Stepping in with soothing, responsive interactions to help a person be able to regulate their emotions.   OR Borrowing the ability to attain a regulated state from another person who is emotionally regulated and responsive to our need for assistance.
First – you need to regulate yourself.  
 
Be aware of own triggers 
Find /create your own system of support  
Find activities, interests to help you regulate (music, movies, hobbies, exercise)  
Find what grounds and anchors you, a source of strength, comfort, and clarity of purpose like personal faith, nature, meditationsSecond - let them borrow some of your regulation.  
  
Be (and remain) present  
Reflect back calm and responsiveness    
Hold spaceThe final step of regulation is to actively teach children how to regulate themselves, giving them tools to use.
  
Mindfulness  
Name It to Tame It    
Creative Expressions of Emotions    
Movement & Rhythm   
Breathing    
Sensory Engagement     
Hunger or Thirst    
Grounding Techniques    
Play  Mona Delahooke https://monadelahooke.com/
Deb Dana https://www.rhythmofregulation.com/
The Whole Brain Child- Dr. Siegel and Dr. Bryson