"However, the Court ruled in Clinton v. Jones, 520 U.S. 681, 117 S.Ct. 1636, 137 L.Ed.2d 945 (1997), that a sitting president does not have presidential immunity from suit over conduct unrelated to his official duties. The holding came in a civil suit brought by Paula Corbin Jones against President Clinton."
(U.S President legal definition of U.S President)

Is there a way a sitting president could extend his immunity in the future? For example, to also cover his activities as owner of private companies?