Yes, it is possible.... to a point. And there are drawbacks. Even if you swap out bones with some hyper-efficient material (like pure graphene), the body may be able to get larger strength wise, but there are disadvantages to the rest of the body:
Heat
The predominant issue with significantly larger (or smaller) creatures comes with heat transfer. Larger veins, more blood, more heat generated, much more difficult to cool. Similarly on the opposite side - if humans were the size of ants, we'd lose heat so fast we would probably die within seconds.
Strength
As explained in this article, the larger your animal gets the greater its overall strength, but the lesser its relative strength. In other words, an ant can lift objects many times its mass. An elephant cannot. So the larger you get, the lower your ability to lift your own arms, legs, etc.
Impact and Function
Ever seen an elephant jump? There comes a point where the extra bone mass is just hell when applied with gravity. The larger you are, the further you have to fall, the greater the gravitational impact.
Even if we remove the effect on the bones by replacing bones with a super-strong version, impact of jumping, running, or other actives has impact on internal organs. Ever tried to sprint when you had a massive migraine? I don't recommend it. This is what it would feel like normally if you were many times your current size.
As @TobyB correctly points out in a comment: the joints would also have to be much stronger or your humanoid/animal would not be able to move very much, also the inner organs would need to have better padding or a simple topple might kill your creature.
That is, more mass is more hell on joints - the joints themselves need to grow more than proportionally with the size and shape of the body in order to handle the cubic increase in mass. Same with padding on the organs: larger internal organs needs more fat scaled to the size and mass of the organ, which is a value greater than the proportional values in our current bodies. Without this, simply walking or running could break joints or cause internal ruptures.
Biomechanics
I think Wikipedia summarizes this nicely:
If an animal were isometrically scaled up by a considerable amount, its relative muscular strength would be severely reduced, since the cross section of its muscles would increase by the square of the scaling factor while its mass would increase by the cube of the scaling factor. As a result of this, cardiovascular and respiratory functions would be severely burdened.
In the case of flying animals, the wing loading would be increased if they were isometrically scaled up, and they would therefore have to fly faster to gain the same amount of lift. Air resistance per unit mass is also higher for smaller animals, which is why a small animal like an ant cannot be seriously injured from impact with the ground after being dropped from any height.
