For images added using Markdown, we are unable to adjust the images sizes.
Hence, if you require to adjust your the image size, you will need to use html code instead.
Instead of a separate CSS file, Isomer uses inline CSS for adjustments of the images. (Not important if you don't understand)
This is how a typical image code will look like.
<img src="/images/filename.jpg" style="width:25%">
We use the style command to control the attributes (width, height, aspect-ratio etc) of the image. We can fix the attribute using an absolute value like the number of pixels (px), a percentage of the original image size (%) or a percentage of the device frame size (vw, vh).
Using px (pixel):
<img src="/images/chicken.jpg" style="width:200px">
Using % (percentage of original size):
<img src="/images/chicken.jpg" style="width:50%">
Using vw (view width):
<img src="/images/chicken.jpg" style="width:25vw">
You can resize your window to see how the images are resized to fit.