This is nice thing to have on hand if your child (or you) is feeling anxious, worried or angry at times.
Talk to them (or you may already know) what helps them to feel better when they feel strong emotions and pop some things in a shoebox or suchlike that they can take when they need it. If they’ve behaved in a way that needs a conversation, give them some time with this first. It’s hard for children (and indeed adults) to talk about something at the time or straight after the event,
I’ve attached a picture with ideas (with Americanised spellings I’m afraid!) but do what works for your child. You could put in a squeezy toy, bubbles (for blowing things away), some mindfulness/other colouring, a favourite book, playdough, pack of cards, a cuddly toy or anything else that helps them.
You might like to have one as well with things that you know help to calm you, It can feel really challenging to be in with the children all the time with no space or the usual boundaries in place. I will personally be including a picture of a bathroom that I can escape to for 5 minutes without one of my children trying to unlock the door with a 1p coin …