Ignition coils don't always have to be replaced when replacing the vehicles spark plugs.
But usually by the time my spark plugs are ready to be replaced on my own vehicles the spark plugs and ignition coils usually have a lot of miles on them.
I personally on my own vehicles replace the spark plugs and ignition coils on my vehicle.
But I only replace the ignition coils every other spark plug change which is then at around 200 K miles.
Your ignition coils can sometimes outlast your vehicles spark plugs but sometimes it's a good idea to go ahead and replace the ignition coils when you do replace the spark plugs just to keep the vehicle running smooth and prevent a break down somewhere.