CodeIgniter4 - How i can add extra 3 fields to a created table using Migration ?

So I should create a new migration fille seperate for each field

No.

or i can just create a migration file using below command ?

Code:

php spark make:migration AddExtraFieldsToEmployeesTable

Yes, but note that you must use a unique classname in all migration classes (now and in the future).

After i can use addField() command in up() and removeFiled() in down() ?

No, you must use addColumn() and dropColumn().
https://codeigniter4.github.io/CodeIgnit...to-a-table
https://codeigniter4.github.io/CodeIgnit...dropcolumn

ci-phpunit-test | CodeIgniter Testing Guide | CodeIgniter 3 to 4 Upgrade Helper