What does "Weird Flex But Ok" mean? I looked up on the Internet but I couldn't get any more!
In contemporary Internet slang, a flex is a boast.
This word is often used in the contemporary Internet cliché (oops, I mean meme): weird flex, but OK.
The meaning is fairly literal, once you take into consideration the slang meaning of flex: That is a strange boast (a strange thing to boast about), but that's OK.
Here's an unhip source explaining the meme (which probably does mean it's morphed into a cliché already): https://www.dailydot.com/unclick/weird-flex-but-ok-meme/