In France, the academic dissertation or thesis is called a thèse and it is reserved for the final work of doctoral candidates. The minimum page length is generally (and not formally) 100 pages (or about 400,000 characters), but is usually several times longer (except for technical theses and for "exact sciences" such as physics and maths).
The body of the thesis must be double spaced. Footnotes, bibliographical entries, long quoted passages, and items in lists and tables may be single spaced.
These patterns can give a "lift" to your writing. Practice them. Try using two or three different patterns for your introductory paragraph and see which introductory paragraph is best; it's often a delicate matter of tone and of knowing who your audience is. Do not forget, though, that your introductory paragraph should also include a thesis statement to let your reader know what your topic is and what you are going to say about that topic.