I work in a company where I mostly do Drupal development. Now it's hard to say anything concrete about your job offer, since we don't really know the company etc. There's not really a reason why doing development with Drupal should be any less coding than doing development with some other PHP framework.
You get a lot for free with Drupal, the whole CMS part, all the modules on drupal.org, and yes there will be some AI configuration, but it's usually not that much. All the configuration part of a Drupal and modules is pretty easy if you know what you're doing. For me I spend around 5% of my time for a project doing configuration, making views (a drupal module you can use to create displays) etc, the rest of my time, I use hacking away in my code editor.
As a drupal developer, you mainly do two things.
- Write code to add functionality
- Write code to alter existing functionality.
Drupal is run is procedural, so there's not much classic OO, instead you write code that gets executed when something happens. Fx a user logs in, then you get a chance to modify the user, do some things like counting how many times the user has logged in.
An important part of Drupal is also presentation. In Drupal we call this theming. Theming is also very code heavy. Drupal is very flexible, so you can overwrite functions used to generate the markup in your theme. These are classic PHP functions. Then there is the whole css, html js part as well.
If you have the chance to do Drupal development, I think you should take it. There is a massive demand for good Drupal developers, that know how Drupal work, and how to use the APIs. It will be something you can use to find your next good job. Knowing some random in house PHP framework, will probably not help you as much in terms of finding your next job.