If one were to need true privacy as you say, shouldn't there be benefit to overlapping security approaches? Ie, use E2EE, use expiring messages, use out-of-ban

If one were to need true privacy as you say, shouldn't there be benefit to overlapping security approaches? Ie, use E2EE, use expiring messages, use out-of-band challenge/accept (ie, recipient has to mention keyword or conversation stays plausibly deniable) all seem applicable.