Can I run drush command from composer with custom script
I was able to do this. Here is a simple example:

First, create a file called import.sh and place it in the scripts folder.

#!/bin/bash

# Exit immediately on errors, and echo commands as they are executed.
set -ex

# Run coniguration import.
cd web
echo "Running coniguration import (config split imoprt)"
drush config-split-import -y

# Clear Cache.
drush cr


Second update composer.json by adding the script to the scripts folder.

"scripts": {
  "import": [
    "./scripts/import.sh"
  ]
},


Now you can run composer import