Not that I'm aware, but there are modified GR theories. In classical GR, the equations can be derived by applying the principle of least action with the Ricci s

Not that I'm aware, but there are modified GR theories. In classical GR, the equations can be derived by applying the principle of least action with the Ricci scalar R being the Langrangian. People are studying what happens if you assume the Lagrangian is a function of R, like R^n or so. It doesn't have the same stigma as MoND, but it's also not that popular. It's also very hard to test for. https://en.wikipedia.org/wiki/F(R)_gravity https://en.wikipedia.org/wiki/F(R)_gravity