Regularly work with your child to increase their emotional vocabulary. During those moments when they become overwhelmed by "big" feelings, help them access those words and name what they are experiencing.
Dan Siegel, MD, author of The Whole-Brain Child, coined the phrase "name it to tame it." When a child's emotions start to get out of control, we want to engage the part of their brain that can help them bring some order to the chaos. Dr. Siegel described the right brain as the emotional side and the left brain as the logical side. Encourageing a child to name the emotion they are feeling engages the logical left brain, which can help them make sense of their experience and calm themselves down. As the logical side of the brain becomes more accessible, a child will have more time to filter and organise their reaction and behaviours and actually choose how they want to respond in the moment. Books like What a Feeling! are great tools for teaching kids new vocabulary words to describe their feelings and emotions.