What is it called when one word in a sentence "downplays" another?

In sentences such as

"I'm a little devastated"

"He's a little obese"

We tend to think of obese and devastated as being on the more extreme end of the scale when describing something, but what is it called when another word is used before it that sort of "downplays" it?

Would calling these contradictions be appropriate, or is there another term?

This is a form of litotes, which does not have to use double negatives, but always employs understatement. Depending on context, it might also be classed as irony, where what is meant is the opposite of what is actually said.

In rhetoric, litotes (/ˈlaɪtətiːz/, US /ˈlɪtətiːz/ or /laɪˈtoʊtiːz/) is a figure of speech in which understatement is employed for rhetorical effect, principally via double negatives. For example, rather than saying that something is attractive (or even very attractive), one might merely say it is "not unattractive".

Litotes is a form of understatement, always deliberate and with the intention of emphasis.

Wikipedia