It is well known that the smaller and the larger of a random sample of size two are positively correlated. The coefficient of correlation is at most one-half, and the upper bound is attained only for rectangular distributions.
"A Characterization of Rectangular Distributions." Ann. Probab. 11 (3) 823 - 826, August, 1983. https://doi.org/10.1214/aop/1176993533