Samsung SM-T820 User Manual page 59

Apps and features
Direct pen input
Fill in forms and write messages using your handwriting with the S Pen.
1
Hover the S Pen over a text field.
2
Tap to open the handwriting field.
3
Write with the S Pen.
If this feature is not activated, launch the Settings app, tap Advanced features → S
Pen → Direct pen input, and then tap the switch to activate it.
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