You could add small aliquots of moderately concentrated HCl while continuously mixing. However, if you are concerned about overshooting to a very low pH value, an alternative would be to add a buffer pH,d to the lowest acceptable pH value. For example, acetate pH 5 Could be used. If you want the final pH actually to reach 5, then acetate pH 4.5 would be more efficient. There would be some natural resistance to overshooting pH 5 because of acetate‘s pKa value.