Most lists of tantrum-taming tips include this one suggestion - head off tantrums before they start.
Make sure kids are well-rested and fed, and that they have activities that keep them engaged, especially when on the go.
You know your own kid’s limits the best, so if you are out running errands, set a time limit that is within their patience level – and yours. Avoid cramming one more item on the to-do list when you know it could lead to a potential tantrum.
At home, have a quiet place ready as a chill-out zone for fussy children that can also serve "time out" zone for those times when a full-blown tantrum takes over.