So, what you're referring to is hair thickness vs. hair density. Thickness is the width of a single strand of hair, while density is the amount of strands in a given surface area. Since titans are pretty much just larger humans, their hair thickness and density are most likely relatively similar. However, since titans have larger heads i.e. more surface area, they would probably have many more strands of hair on their scalp than a human, but with a similar thickness and density (we have on average 22,000 strands of hair per sq. inch).
reference: https://prose.com/blog/hair-thick-dense-difference.php
It's probably the same if you think that they're just xl ppl, like how ppl with dwarfish/gigantism have like the average human hair strand diameter. (=・ω・=)
is a single strand of a titan's hair thicker than human hair or do they just have more of the same diameter hair please i cant sleep