NX Release: 2206
You can see whether the sketch is fully constrained or not in Siemens NX. A fully constrained sketch means all curves and points in the sketch are fixed by constraints or dimensions.
To see sketch is fully constrained or how many curves in the sketch can move freely in the sketch you can look at the Cue/Status bar at the bottom of the NX graphics window.
If the sketch is fully defined with constraints and dimensions, on the Cue/Status line you will see the “Sketch is fully constrained”

In the figure: Rectangele’s one corner is fixed on the sketch origin and other corners are defined with dimensions

If I delete one of the dimensions, the description on the Cue/Status line changes to “Sketch is partially defined with 3 movable curve(s)”