Cthulhu has masculine energy, from my point of view. I don't know why!
Oh, I absolutely agree
But what makes these energies fit, what makes a think feel feminine beyond a bow on it's head? What makes a thing feel masculine, what makes a thing feel neither?
Sorry, didn’t realize you meant the question earnestly. So, this is entirely culture-dependent, because masculinity and femininity are social constructs. But, in most of the modern developed world, masculinity is treated as the default. This is why we often use gender signifiers like a bow, a skirt, makeup, jewelry, an hourglass figure, etc. because things will tend to be assumed masculine unless otherwise specified. For an example, look no further than Men’s and Women’s restroom signs - the former is an unadorned stick figure, while the latter is the same stick figure with a silhouette that flairs near the knees like a skirt.
Cthulhu’s description in the original short story is deliberately somewhat unclear, but the statue representing him is described in a lot of detail, and it doesn’t mention any such common gender signifiers. In addition, visual depictions tend to give Cthulu broad shoulders, large and well defined muscles, which tend to be associated with masculinity.
As for less overt traits that convey masculinity or femininity, the former tends to be associated with power, strength, directness, high-energy activity, violence, etc. The latter tends to be associated with grace, gentleness, passivity, warmth, nurturing, etc. Again, these are cultural associations and not
inherently tied to gender or sex. But, within the social structures we exist within, those are the things most commonly associated with masculine or feminine “energy”.