Is it normal for words to bulge when written with hard pen?

It is normal.

Hard-pen calligraphy is a calligraphy technique using a hard pen tip, which is characterized by clear lines and square strokes. Because hard-pen writing uses a hard nib, it exerts a certain amount of pressure on the paper when writing, thus forming a bulging feeling on the paper. This bulging feeling is caused by the friction and pressure of the pen tip against the paper causing the ink to bulge slightly on the paper. This protruding feeling gives people a natural and textured visual effect, and is also one of the unique charms of hard-pen calligraphy.