Set width and height values for images

[Alpacala]

Hello friends, I am writing here because the subject is related to SEO. When I examined my page on Google Pagespeed tests, it says the image does not have a clearly specified width and height value. In terms of SEO compatibility, should images in Responsive designs be given a width and height value in pixels? As you know, it is given as a percentage according to the screen. If it should be given, for example, the image is 1000 X 1000 but we want it to appear as 400 X 400 on the page, should it be 1000 X 1000 or 400 X 400?