These are the requirements for cover art:
File format must be .jpg or .jpeg.
File size must be no larger than 5Mb.
Image dimensions must be at least 1600x1600 pixels.
The album title on your cover art must match the title you listed for your album.
Your cover art cannot include blurry/pixelated images, cut off images/text, rotated images, logos, pornography, references to iTunes/Spotify/etc., references to physical releases (CD, compact disk), Nazi propaganda, or barcodes.
Your cover art can be explicit.