GoodNotes lets you type texts with the keyboard using the Text Tool. Choose the Text Tool in the toolbar and then tap anywhere on the page to insert a text box. This will automatically bring up the iOS screen keyboard or will allow typing with an external keyboard.
Use the brush icon in the contextual area options to format text
You can format the text box by adding borders, background color, and padding. Selected text can be styled as well with different fonts, colors, sizes, etc.
To format text in an existing textbox, please select the text you want to format and tap the brush icon in the toolbar.