Hi Randy, Welcome!
As a rule of thumb, quality non enhancing impregnators will not change the grout color. Stay away from topical sealers and finishes. To avoid clouding as Art mentioned, use a solvent based sealer. Dupont Stone Tech Impregnator Pro and Surface Treatment Technologies SB have both proven to be excellent stable impregnators for me. There will be an initial color change on application that will dry out after the carriers have evaporated.
Are you only doing the grout? Sanded or unsanded? Floor or walls?