please explain what exactly you wants to know, every square can be circumscribed and inscribed
The condition for the quadrilateral to be circumscribable (by a circle) is that both pairs of opposite angles should add up to 180°. The condition for it to be inscribable is that the sum of the lengths of both pairs of opposite sides should be the same. Put those two conditions together and I guess you have the condition given by earboth.
In fact, you can choose any four lengths a, b, c, d satisfying a+c = b+d, and there will be a quadrilateral having those four lengths for its sides which is both inscribable and circumscribable. If the vertices are A, B, C, D, with AB = a, BC = b, CD = c and DA = d, then the length x of the diagonal AC is given by
Once you know x, it is easy to draw the quadrilateral. For example, if a=3, b=4, c=6, d=5, then and the quadrilateral looks like the picture below. (The incircle is not exactly located, because I was guessing the position of its centre and didn't get it quite right.)