how to display a fallback logo when the one set in config isn't supported by terminal?

[GrassBlock1]

I used fastfetch in my fish motd and the logo is a png image like this:

It's supported by kitty, but when I switched to terminals like alacritty and the one in IntelliJ idea(which seems to be xterm-256color) and the image logo are not supported:

And this is my config for logos in fastfetch:

"logo": {
        "type": "auto",
        "source": "/home/grassblock/Pictures/1017124-new.png",
        "height": 6
    }

and my greeting section config.fish:

# greeting
function fish_greeting
  echo ""
  fastfetch -c $__fish_config_dir/motd.jsonc #this stands for the config above
  echo -e "\nWelcome to fish@$TERM, $USER!"
end
# greeting end

So is there any way to easily set a logo as a fallback? I had searched issues and discussions and seems there's no similar situations for this.

thanks in advance.

[CarterLi]

function fish_greeting
    if [ $TERM = xterm-kitty ]
        fastfetch -c $__fish_config_dir/motd.jsonc
    else
        fastfetch -c $__fish_config_dir/motd.jsonc --logo-type builtin
    end
end

[GrassBlock1]

thanks for quick reply! I tried this in my config.fish and it works.
But I still have two questions:

1. Is there any way to tell fastfetch to use a small logo via the command line options in this circumstance? I tried --logo-type small but it seems doesn't work.
2. Some terminals like konsole report themselves in $TERM as xterm-256color,but they do support display images:
   
   Is there any solutions for them?

[CarterLi]

I tried --logo-type small but it seems doesn't work.

Try -l arch-small

[GrassBlock1]

I tried --logo-type small but it seems doesn't work.

Try -l arch-small

I don't think it works....(the config file was copied as-is, from the original one)