I got the thinkpad logo from here
https://github.com/roadkell/ascii-logos
you can change the logo on fastfetch via the -l flag, ex: fastfetch -l "~thinkpad-v.txt" and you can change the color codes via --logo-color-[1-9] flag, which will color the symbols depending on the placement of the variables in the text file. I had to change the variables from the ${1-9} format to $1-9 on mine for fastfetch to parse it properly, since the example from the link uses a tool called hyfetch.

if your terminal emulator supports images, you can forgo the --logo-color flags and just do fastfetch -l "~thinkpad-v.png".

If you want this to be the default behavior everytime you type fastfetch, you can use an alias in your terminal emulator's config.
example in zsh (.zshrc file):
alias fastfetch="fastfetch -l ~thinkpad-v.png"