Currently, if you're going to schedule an Email and SMS in the conversations. You don't have the ability to edit the message, only cancel. These type of scheduled emails or texts in the conversations are our own personal followups tailored for a specific contact. It sometimes needs to be updated depending on how the conversation is going. Also, it should be BY DEFAULT, NOT SEND IF THE CONTACT RESPONDED BEFORE THE SCHEDULED DATE AND TIME. (sorry for the CAPS)
Here are the related ideas at the time of writing in all of Highlevel suite:
  1. https://ideas.gohighlevel.com/email/p/ability-to-pause-and-edit-scheduled-campaigns
  2. https://ideas.gohighlevel.com/lcphonesystem/p/ability-to-edit-scheduled-bulk-sms-email-requests
  3. https://ideas.gohighlevel.com/conversations/p/can-the-from-name-stay-the-same-when-a-scheduled-email-campaign-is-updated-inste
  4. https://ideas.gohighlevel.com/email/p/edit-or-switch-to-draft-emails-that-are-scheduled-but-not-sent
  5. https://ideas.gohighlevel.com/templates/p/editdelete-scheduled-emails
  6. https://ideas.gohighlevel.com/conversations/p/cancel-a-scheduled-sms-if-contact-responds
  7. https://ideas.gohighlevel.com/ad-reporting-and-attribution/p/please-allow-us-to-edit-emails-already-scheduled