The above posts are correct, and that the precise impact (or magnitude) depends on the individual airfoil. I did however spend some time looking at NACA, NASA, and other technical papers yesterday. I think it's fair to say that with decreasing Reynolds numbers, the CL curve is generally lower and not as smooth and well behaved at lower Reynolds numbers. The CD is similarly less well behaved and generally higher than the same airfoil at high Reynolds numbers. See figures 6 and 8 in note 1.
Note 1:
https://arc.aiaa.org/doi/pdf/10.2514/1.C034415