Click "Filters" on the menu bar and go to "ABCs." Select "Diffuse Light" to add a 3D effect to the text. Go back to the ABCs menu and apply the "Black outline" effect as well to emphasize the 3D look.

When you partially turn the upper right corner of a Photoshop image, you heighten the 3D effect by showing something behind that part of the image; gray works nicely as a background color.

Tap then wait for the image to be processed. Preview the 3D effect by moving your phone. Add text and any other content to your post, then tap ‘Post’. Tips for better results.