Keyboard Shortcuts To Increase or Decrease Font Size
When you have highlighted text in Photoshop, press Ctrl + Shift >/< (Windows) or Command + Option >/< (macOS) to increase/decrease the size of your text by 1 point.
You can also press Ctrl Alt Shift >/< (Windows) or Command Option Shift >/< (macOS) to increase/decrease in 5-point increments.