Follow the steps below to change the font size.
1. Click on the text frame and highlight the text that you'd like to increase or decrease the font size of.
Notice: Font size can vary by individual characters within a single text frame. That means you can have a single word with multiple character sizes.
2. Click on the font icon button if it's not already open (It's the default tool view for text tools, so it's likely to already be open and this action is unnecessary).
3. From here you can simply click on the up or down arrows within the font size stepper.
Notice: You can also highlight the font size number and type in the desired font size followed by clicking enter to apply.