<div class="box">
<span>
<img src="https://picsum.photos/id/127/300/200" alt="" />
</span>
</div>
The image has a width of 300px and height of 200px.
Although the image is a child element of the span, the height of the span is only 21px, not 200px or greater than 200px.
I believe I have found the explanation, thank you everybody!
10.6.1 Inline, non-replaced elements
The height of the content area should be based on the font