Stroke (Outer) lets you add an outline to text on a colored background.
First, select ①the Material tool and choose a background. Tap ②Geometry Pattern (Color).
Here, we have selected ①Watercolor dot.
Tap on ①✓ to apply the material.
Open ①the Layer window, and move the material from the previous step②underneath the illustration layer.
Add ①a new layer and select ②layer.
From ①the Tool Selection window, select ②Filter.
Select ①Stroke (Outer).
Drag ①the sliders left and right to make adjustments.