This shouldn't be a feature request, but instead recognized as an urgent need for our privacy and safety.
I am sick of Twilio or other tech company spying on my texts and blocking them if I use any word they consider verboten, such as cannabis or weed, when replying to guests' inquiries.
What my guests and I write to each other is none of anybody else's business. We don't live in North Korea, after all.
Introducing End-to-end Encryption for Twilio IP Messaging with Virgil Security℠
SMS by design is plain text, not encrypted: https://www.howtogeek.com/709373/why-sms-text-messages-arent-private-or-secure/ -- since this is a standard protocol there is no way to force encryption on SMS.
To get encryption, you need to use a completely different secure messenger app. The Twilio IP Messaging link you referenced is a secure chat app: https://www.twilio.com/blog/announcing-ip-messaging-apis-for-embedded-chat-html, or something else like Signal, etc.