There is a useful feature when PowerPoint autofit your text. See how to use it:
- Go to ribbon to the Insert tab.
- Click Text Box.
- Click inside a slide where you want to put your text.
- Type your text inside a text box.
- On the right side Format Shape menu appeared. Click Size & Properties (3rd button).
- In Text Box there is an option Resize shape to fit text. Check it.
Note: Autofit is really important when you will launch your presentation on different screen resolutions. Be aware that your slide will look on the other resolution or on widescreen.