A good learning objective is concrete and can be checked. "Understand GDPR" is hard to measure. "Be able to decide whether a piece of information is personal data" can be checked with a few questions.
Start with a verb that describes an action: explain, choose, fill in, find. Keep it to three to five objectives per course. If there are more, it is often two courses.
The learning objectives make the rest of the work easier. Any content that does not help reach an objective can be cut. And the quiz should check exactly the objectives.