Is there a way to make a text template?

Currently this is not supported on the RC app (mobile and desktop).

But if you have a High Volume SMS number, you can use the RingCentral Labs - High volume SMS app to send campaigns with predefined text template in a .CSV file. The app will support this feature for standard SMS numbers also in the next release. Using the app, you cannot pin (store) somewhere, nor you can share it with other users. But you can store it anywhere in your local machine and share the file with other users as you need.

You can see the instruction from the Help page of the app. But here is the screenshot of it.

Any update on this? Would love to see a signature option or template option for responses. This is becoming a pilar of most sms programs that are on the market.

Update on what? Have you tried the SMS Campaigns app?