What size is a Vietnam e-visa photo?
Four by six centimeters, upright. That makes it a 2:3 rectangle, taller than it is wide, and not a square. The official guide stops there: it sets no head height, eye line or pixel count.
Since the photo is uploaded rather than mailed, the proportion is what counts. Crop a sharp, recent picture to 4 x 6 and make sure the face points straight at the lens.
Source: evisa.gov.vn
