How to apply size of image in toml file

i am working with hello friend theme but I am not able to resize my background image is any way to apply size and align of image in toml file ?

No, there is not.

then how did this gyu did that ? (https://www.matteomalvica.com/) any idea

Don’t know what he has done in this web site.
But jmooring was responding to you direct question. Nothing can be done in frontmatter.

What you have to do is to use .Resize and other image transform in your partials.
Then you can get size information from the frontmatter. But the magic happens in the partials.

see Image Processing | Hugo

I think the site uses this theme: GitHub - rhazdon/hugo-theme-hello-friend-ng: Pretty basic theme for Hugo that covers all of the essentials. All you have to do is start typing!

Hugo doesn’t resize this image (which is not a backround image).