You’re requesting that the other side delete the message after a set period of time. The client on the other side could save the message instead, but realistica

You’re requesting that the other side delete the message after a set period of time. The client on the other side could save the message instead, but realistically it probably won’t. This depends on you trusting the other conversation party - but it would in any case, as there are so many ways to save a message that’s on your device. Even if you assume the most draconian, user-hostile device imaginable, all it takes is a camera pointed at the screen to defeat. It’s just not worth it.