Question: Are there any cross-platform matrix clients which prevents any messages from being sent/received that are not end-to-end encrypted?

I really like the idea of Matrix, but–as a general rule–I don’t use communication platforms that allow for unencrypted messages to be sent. The risk for accidental user-error is too great, especially if rolled-out to non-technical users. IMHO, it’s just better to have users install apps that cannot, under any circumstances, transmit messages that are not end-to-end encrypted.

So, I’m wondering if there is an app for Matrix available that simply doesn’t allow users to send or receive messages that are not end-to-end encrypted. Note: I’m not looking for a user-configurable option to enable/disable this. I want it to entirely block the possibility for messages to be sent or received if they are not going to be end-to-end encrypted.

Do any such apps exist? Ideally ones for all of Linux, Windows, Mac, Android, and iPhone?