If you recently switched to Signal, and want to send automated reply/ predefined responses to incoming messages, then the Auto-responder app will do it for you. You can create rules to respond to individual chat and group chat as per your interest. The AutoResponder for Signal app will help you react to messages from specific (or all) contacts when you’re busy. And, it will make things more transparent.
Steps to Add Auto-Reply Facility to Signal Private Messenger
You have created a rule to auto-respond to incoming messages in Signal. For advanced features like welcome messages and Tasker integration requires the pro version of the app. FYI, the AutoResponder for Signal app uses notification access to identify incoming messages on Signal. You don’t need to enter your Signal credentials into the app. More Resources:
How to Hide Your IP Address When Calling Via SignalHow to Make Signal Your Default Messaging App on AndroidAssign Custom Notification Tone for Chat Threads in Google Messages App