Fixed size layouts

When you select a fixed size widget that is not a child
of a flex widget, fixed size layout information will appear
in the Layout Explorer. You can see size, constraint, and padding
information for both the selected widget and its nearest upstream
RenderObject.

Visual debugging

The Flutter Inspector provides several options for visually debugging your app.
These are the options available from the inspector within Flutter DevTools.

Slow animations

When enabled, this option runs animations 5 times slower for easier visual
inspection.
This can be useful if you want to carefully observe and tweak an animation that
doesn’t look quite right.

This can also be set in code:

This slows the animations by 5x.

See also

The following links provide more info.

Flutter documentation: timeDilation property

The following screen recordings show before and after slowing an animation.