Changing islands falloff at one area

What I am trying to do is take an island with about 12km drop off, and change an inlet and a lake falloff to something else. I tried a few things and it isn’t coming out right. Any suggestions?

To make the falloff steeper in one area, I tend to use additional shapes that have sharper falloffs defined and then layer them atop the first one eg for a rocky point vs beaches.

The same can be done in reverse to make the falloff gentler – pull back the base shape away from the area you want, then create a second shape atop that area with a gentle falloff