The following steps will help you change the text size.

Step 1 − Select the text the case of which you want to change.

Step 2 − Go to the Font group under the Home ribbon.

Step 3 − From the Font Size dropdown, select the size you want to use for your text.

Step 4 − Click on your choice to change the font size for the selected portion of text.

Step 5 − If you want to change the font size in steps you can also use the Increase/ Decrease Font Size options.