If the mass is two hydrogen atoms (protons) the force (weight) will
be twice the force (weight) of one proton. If you have a billion
protons the force will be a billion time more than one. If the mass
is a billion atoms the force will still depend upon the total
number of protons (and neutrons). Water seeks its own level because
the earth attracts each water molecule separately but can attract
an ice cube collectively.
The mass will also exhibit a force (weight) depending upon how
close it is to the center of gravity of the attracting body (but
must be above the surface). The force will diminish at greater
distances from the center of gravity in accordance with the inverse
square law which describes the strength of the (3D) field. As
rocket ships leave the earth they feel less and less gravitational
force. The attraction is spread over larger and larger concentric
spheres, where the areas of the spheres increase in proportion to
the square of their radii. At the center of the earth the
gravitational attraction is zero (because there is as much mass
above the center in every radial direction).