This shader adds several types and combinations of 2D sprites outlines.
Outline Enabled
Outline Connected Alpha: main color's alpha is shared
Outline Width
Outline Modes: Solid, Gradient and Images
Outline Shapes: Contour and Frame
Outline Positions (Frame only): Outside, Inside (over and under image)
Solid:
    Outline Color
Gradient:
    1) Weight
    2) Angle (contour only)
    3) 2 Gradient colors
Image:
    1) Frame Mode: Stretch, Tile
        a) Tiling
        b) Offset
    2) Image color overlay

PS: to be able to fully work with this plugin, clock on the sprite in your Assets, then in the Inspector, click on "MeshType" and select "Full Rect", then Apply at the bottom