Turning off the message sent noise for text messages

I'm trying to work out how to turn off the sound that my Oneplus 8 makes every time I send a text message. Does anyone know how? turning off text message notification sounds doesn't do it, it just removes the message received sound, which I want to keep intact.

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Problem solved thanks to /u/TheManWithSaltHair : If anyone is googling/searching for it: It was of course its own settings menu within the text message menu, accessed through the three dots on the upper right corner.