Taylor Swift is horning in on the life of Kylie Jenner in a big way ... the singer took up a bigger billboard than hers, right across the street.
A new billboard featuring Taylor's mug promoting her new single, "Look What You Made Me Do," moved in across the street from a "Life of Kylie" billboard 50 feet away on the corner of Santa Monica Blvd. and La Cienega in WeHo.
By the looks on their faces ... we'd say Taylor's got more to prove here -- and more turf to claim in this epic billboard face-off.
Taylor isn't known to have beef with Kylie personally, but we all know she's not on good terms with Kim and Kanye ... and probably, by extension, the whole Kardashian clan.
How about picking on someone your own size, Tay?