Definitely wouldn’t break the encryption itself.

I think the way it could work is to send a letter to each of the messaging apps saying that they are now legally required to use the EU’s encryption keys and make the messages available to the EU.

Then they would make it so that the apps that don’t comply are not available in the app stores by pressuring google and apple respectively.

I think this is the reason why for example telegram is not end to end encrypted by default - as some regions require them to be able to access users info.

Software you’re using on your own wouldn’t be effected, but wouldn’t necessarily be legal either.

People who are technically savvy could get around it, but the vast majority of people just assume that their private messages are private.