It looks like a word search and you can find some words in it, but it doesn't really look like a word search because most of letters don't form words. If you look closely, words like ALICE and CURIOUSER jump out a few times, along with some fragments of other words. This should lead you to conclude that there are some Alice in Wonderland things going on in the grid, and you can start to pull out other words, but some of them have extra letters interspersed. If you look at the strings that seem to form words but aren't directly related to Alice in Wonderland, you'll be like "aha! this sounds just like a Taylor Swift lyric! I love her!".
Once you get over your excitement of Taylor Swift, you can find that the grids are composed of two interleaved strings of letters: each grid contains the beginning chunk of a Taylor Swift song and the beginning chunk of a section of Alice's Adventures in Wonderland. The little grid contains the lyrics to "Never Grow Up", which is fittingly about being little, and the big grid contains the lyrics to "Mean", which is fittingly about being big. The Alice text in the little grid is fittingly from when she becomes little for the first time, and the Alice text in the big grid is fittingly from when she becomes big for the first time.
Here's what the grids should look like when you identify which letter corresponds to which text, coloring the Taylor Swift lyrics red (of course) and the Alice text blue (of course). Then you're like "Okay, what do I do now with this grid that contains these two interspersed strings?". The puzzle's titled "Black and White"; if you make one string black and the other string white (and do the opposite for the other grid ... well, because they're opposites), you get either a QR code or the inverse of a QR code! Here are the QR codes:
|Little QR||Big QR|
There are some potential ambiguities in the grids, but each pixel in the QR code is formed from a 2x2 block of letters with the same color, so if you come across an ambiguity, you can resolve it that way.
Once you scan these, you get two messages. For the little one, you get "LIKE TRYING TO KNOW SOMEBLANK YOUVE NEVER MET", and for the big one, you get "A LITTLE KID WITH GLASSES IN A TWIN BLANKD BED".
At this point, you'll be like "More Taylor Swift!!!!" but contain your excitement and resist the urge to watch Taylor Swift videos, because you need to solve this puzzle. When you look up these lyrics (the little one is from "Red" and the big one is from "All Too Well"), you see that each one has part of it missing and replaced by "BLANK". The little one is missing BODY and the big one is missing SIZE.
Now you can say, "Aha! I see! Alice turns little before she turns big, so the missing word from the little message should go before the missing word from the big message." If you put them together in that order, you get the answer BODY SIZE.