You are on the right track.
To start with, you can use fsurf without needing to use symbolic expressions, you just need to switch to using either anonymous functions or function handles.
r = 4;
x = @(phi, theta) r.*sin(phi).*cos(theta);
y = @(phi, theta) r.*sin(phi).*sin(theta);
z = @(phi, theta) r.*cos(phi);
fsurf(x,y,z,[0 pi/2 0 2*pi])
However, I don't think those are the right equations for what you want to draw.
I believe you want to fix phi and vary both r and theta. I believe this may be closer to what you are looking for.
Note that I switched x and z so that the cone was on it's side.
figure
phi = deg2rad(60);
x = @(r, theta) r.*cos(phi);
y = @(r, theta) r.*sin(phi).*sin(theta);
z = @(r, theta) r.*sin(phi).*cos(theta);
fsurf(x,y,z,[0 4 0 2*pi])
