This category of words is called qualifiers, and they indicate "to what degree" for adjectives and adverbs.

Other qualifiers include words like "rather", "quite", and "very".

they're adverbs!

specifically, kinda and sorta are contractions of the qualifying adverb phrases kind of and sort of whereas hella serves as an alternate form of the intensifying adverb phrase "...as hell", eg:

kind of sketchy

sort of sketchy

sketchy as hell

These are "degree adverbs" and change the intensity of the following word or words.

• Meccha - Japanese slang like "Hella"
• Fucking - "fucking crazy"
• Really - "really crazy"
• Somewhat - "somewhat crazy"

Edit: misread the question.