When a child or toddler swallows a coin it's usually not a cause for concern unless the child or toddler is choking on the coin they swallowed.
Then if they're choking on the coin they swallowed then you need to perform the heimlich maneuver on the child or toddler to get the coin out of the child or toddlers throat if possible.
If you cannot get the coin to come up and the child is having trouble breathing then you should contact 911 but if the child is breathing then they're not choking and there's no need most times for medical services.
But if you want too then taking the child or toddler to urgent care or the emergency room to get checked out certainly would not hurt anything.
I remember years ago when I was 4 years old and I swallowed a penny I found on the floor and I never choked on it and likely it just came out in my poop later on.