: How the text appears on screen (e.g., as floating bubbles or a close-up of the screen) is usually decided by the director, so you don't need to over-describe the visual effects in your script.
For more specific guidance, you can explore detailed advice from Screenplay Formatting Tips or No Film School . Send your Scripts
: If two characters are texting back and forth in different locations, you can use an INTERCUT heading, similar to a phone conversation. Tips for Effective Texting Scenes : How the text appears on screen (e