The conclusion is that last thing that the examiner reads before they write their report, and it can shape their attitude to the entire thesis. This adds something a little different to your chapter and allows you to demonstrate how this dissertation has affected you as an academic.
A good way to do this is to simply display your contributions in a bulleted list. In a PhD thesis you may like to indicate some potential for post-doctoral work. Writing a conclusion requires you to have some distance on the thesis.
First of all, your conclusion must describe contributions of your study. Yes, you really do need to make a good last impression. It is often tempting to go off at a tangent and to say things that are completely unrelated to the topic. Always be very careful to check what the conventions are in the discipline you are working in, and ideally, it is best to look at examples of past students' work so that you can see what you are aiming for.
Check what the expectations are in your own department. The objectives generally stem from the overall aim and explain how that aim will be met. Some people believe mistakenly that a conclusion is the place for you to relax and 'say whatever you want'.
This will pave the way and give you the structure you need for your dissertation conclusion.