You can edit a collider's geometry manually or have Unity generate its shape automatically.
Unity automatically generates a collider's geometry when you drag a sprite into the scene and add a Collider 2D component to it. The generated collider shape matches the outline of the sprite as close as possible.
To edit the collider's shape:
Select Edit Collider
in the Inspector window to edit the collider's geometry. You can also access the collider's editing mode from the Tools overlay in the Scene view window.
The Edit Collider icon located at the bottom of the Tools overlay.
To move an existing vertex, select and hold it, then move it to a new location.
To create a new vertex, hover your cursor over the outline of the collider's shape. A dot shows the position of the cursor on the collider's geometry. Click on the dot to create a new vertex at that position.
To remove a vertex, hold Ctrl (macOS:Cmd) while hovering your cursor over the edges of the collider's geometry, which turn red. Click the red edges to remove the vertex that connects them.
Exit the collider editing mode by selecting Edit Collider in the Inspector window or Tools overlay again.
