Well Laravel is just a framework. A framework gives you some tools and function to make it easier for yourself. For example the migrations, the database seeds, the form request classes and so on. They make it easier for you do to stuff that you have to programme yourself if you are not using a framework.
However behind each framework there is a philosophy and if you don't follow that philosophy you might have a hard time using a framework. For instance the facades in Laravel. Some developers call it static functions some don't even want to call it facades at all. You can use them or not, it's up to you.
So a framework helps you to get from A to Z in a much easier and structured way if you know the framework. However it's always good to know how PHP works without Laravel. Let's say you need to build a specific feature and that doesn't really require Laravel, just old school PHP. Now if you only know Laravel, you will have a hard time creating this stuff. It's always good to have a basic knowledge of a certain language. Most developers start creating some stuff for them self to learn the basic and then move on to a framework