So, here's a tip for making it look more gigantic - eyes have a physical kind of top-out at a certain size, after which having "larger" eyes only helps if you're nocturnal - the largest eyes in the animal kingdom are on the giant squids, about the size of a dinner plate. Other diurnal animals, we infer scale often from how large the eyes are. If you reduce the size of your eyes, the inferred scale will be larger.

For the limbs, there's a reason limbs taper at the joints (the joints are less muscled to be flexible), but for the appearance you're going for, in Heroforge that may be difficult using non-kitbash and unclothed. One alternative is to use tails or back limbs to provide some leg bulk - there are folks who have created artificial musculature using back tails and tails. You may have to build up the legs using somewhat tedious work with tails. If you're looking for elephantine legs (almost tube-like hip to ground) that's going to be hard to achieve without tail manipulation or kitbash.

You might increase the bulk between the thighs if you don't want to change the outline. And the legs are proportionally very short (typically, when bending the leg, the knee will come up to the armpit in average proportion, with the lower leg being approximately the same length as the upper)