Do these squares overlap?
Python, 33 bytes

lambda x,y,k,X,Y,K:k&gt;X-x&gt;-K&lt;Y-y&lt;k

Python supports chains of inequalities even when they point opposite directions.
The x-coordinate intervals [x,x+k) and [X,X+K) overlap as long as neither one is fully to the right of the other, which means that each interval's left endpoint is left of the other interval's right endpoint.
x&lt;X+K
X&lt;x+k

The can be combined into a joint inequality -K&lt;X-x&lt;k. Writing the same for y-coordinates and splicing them at -K gives the expression
k&gt;X-x&gt;-K&lt;Y-y&lt;k