The phrase itself is everyday spoken French, and ça c'est vrai ça works online less as a quote from a known scene than as a ready made agreement sound. Its short length and repeated structure made it easy to lift, share and drop into other clips, where it functions like a spoken checkmark. French speaking users circulate it on soundboards and in chats to validate a joke, a complaint or an obvious truth, and the lack of context around the recording is part of why it fits so many situations.