A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
Hello Sunny,
Thank you for reaching out to the community forum!
In PowerPoint for iPhone or iPad, there isn't a direct feature to automatically change the font size of a paragraph to fill the screen without adding lines.
However, you can manually adjust the font size of the text to make it fill the screen by selecting the text box, tapping on the font size option, and increasing the size until it fills the screen.
I appreciate your understanding and cooperation. Have a good day!
Sincerely
Sam | Microsoft Community Moderator.