Choose Product / object, then “Meesho / Amazon / Flipkart square”. The download is a square PNG. The area outside the product is #FFFFFF, and the product sits in the middle with padding. The long side is at most 1000 pixels.
This preset is PhotoJhat's, for a clean listing photo. It is not a claim that Meesho, Amazon or Flipkart require these pixels.
Meesho's lesson on listing a catalogue says to add a sharp, clear image of the front of the product. The clothes and shirt pages say to upload JPEG images without a logo or watermark, and not to use a partial product image or a prop. How to sell on Meesho says the detailed image guidelines are in the Supplier Panel. Read that panel for the catalogue you are uploading.
This page does not quote an Amazon or Flipkart pixel size. Seller image rules live in the account you list with, and they change. Use the white square as a starting file, then match the form in front of you.
Meesho's public lessons do not say that. They ask for a sharp, clear front image, JPEG, with no logo or watermark, and for clothes they say not to use a partial view or a prop. The Supplier Panel holds the detailed image rules. The white square here is PhotoJhat's preset.
Check the listing form you are using. This page does not quote a pixel size from Amazon or Flipkart, because those seller rules were not copied into this page. The file is square, white #FFFFFF, and at most 1000 pixels on a side.
PNG keeps the white at exactly #FFFFFF. A JPEG can shift white a little. If a form insists on JPEG, export or convert the PNG after you have checked the white.