Modern weapons are more energetic than chemical bonds are.  Graphine is no exception.

A Newtonian Penetrator (if the energy levels are low enough that "solid" still matters) or a Fluid Penetrator (if not) model is how deep a given weapon penetrates armor, and it really doesn't care about chemical bonds.  It cares about density and thickness.

Modern anti-tank weapons fire high-density narrow jets to penetrate the target's high-density angled (to increase depth) plates.

It is far easier to make a really long, narrow penetrating weapon than it is to cover every inch of something with a thick layer of dense armor.  So armor has lost.

Since WW1, static fortifications have lost.  Having ridiculously thick armor (in the form of Earthworks, trenches, etc) still gets overrun by mass artillery or other "bunker busting" technology.

Basically, in order to stop a 1 inch long bullet, you need more than 1 inch of the same density material in the bullet *all over your body*.  And if you can carry that much armor due to "power armor", you could just carry a heavier gun that fires longer bullets.

Worse, anti-tank missiles mean you can fire a weapon whose "bullet" is longer than the weapon itself.

Non-chemistry based defences could pull off defence beating offence again: Bullets shooting bullets out of the air, force fields that aren't chemistry based, and other relatively implausible technologies.

As a plausible variant of "bullets shooting bullets", warfare where you have swarms of various scale drones.  The goal is to *spot* your foe, at which point sufficient ordinance is used to destroy them.  Offence becomes a matter of gaining LOS with your drones; defence is getting LOS on their drones before they get LOS on your target.  Everyone is using high-accuracy payloads that disable targets trivially, with smaller amounts of high-penetration payloads to nullify "just send a tank" options.

But this looks nothing at all like soldiers walking around in super high-tech plate armor.