First, right-click the taskbar and select “Taskbar Settings.” When Settings opens to Personalization > Taskbar, open the “Taskbar Corner Icons” menu if necessary by clicking it. When the “Taskbar Corner Icons” menu expands, flip the “Pen Menu” switch to the “On” position.

Tap the keyboard button at the bottom right corner of the touch keyboard. Tap the handwriting keyboard icon, which looks like a pen over an empty panel.