I'd say in the UK a phrase like "What even is steak?" would be more expected of a teenager than anyone else; perhaps because they tend to over exaggerate more in conversation. However a phrase like "Even Anthony liked it." is perfectly common and wouldn't tend towards being used more by any particular segment of the population - this is an expression about the person mentioned, surprise that they liked it more than it is about the speaker using the phrase as emphasis.
A: "Why even would you do that?" [as opposed to "Why would you even do that?"
B: "Because reasons"
"Even Anthony liked it" could well be phrased "Anthony also liked it" but you lose something of the surprise - in the first phrase there is an expectation that Anthony wouldn't normally like that sort of thing.
A: "Why even would you do that?" [as opposed to "Why would you even do that?" B: "Because reasons"
"Even Anthony liked it" could well be phrased "Anthony also liked it" but you lose something of the surprise - in the first phrase there is an expectation that Anthony wouldn't normally like that sort of thing.