To follow suit is to do the same thing somebody else has just done. One shop drops its prices on Monday and the whole street has by Friday.
No article, and no preposition — the phrase takes nothing after it, which is unusual enough that learners keep trying to add one. It comes from card games, where you must play the same suit that was led, and the original rule is still audible in it: you are not copying out of admiration, you are doing what the situation now requires.
1phrasefollow suitTo do the same as somebody else has just done.
“One shop cut its prices and the rest will follow suit.”
follow suit is an act of copying what went before.
Practised in Common Word Pairs