• LinkedIn Profile Picture Size: 400 x 400 px
• LinkedIn Cover Photo Size: 1584 x 396 px

For LinkedIn Company pages: Banner image: minimum of 1536 x 768 pixels, PNG/JPEG/GIF format, 2 MB max, horizontal design, the image should be much wider than long. Logo: minimum size 60 x 60 pixels, 400 x 400 pixel is the recommended size for the square design PNG/JPEG/GIF format, max size of 4 MB.

Credit: https://postcron.com/en/blog/social-media-image-dimensions-sizes/