The new 1.13 textures, if that is what you are referring to, are not currently out yet, but will be coming out as it's own "update" between 1.13 and 1.15. At the moment, you can download the new textures on the Minecraft website minecraft.net (however, the pack is in the 1.12 format). Alternatively, you can download a converted pack by 3XH6R (finished by me), found at
https://www.planetminecraft.com/texture_pack/1-13-default/