Is it possible to make a DVD of my iMovie

Yes. Assuming that you want a DVD with themes, menus, scene selection, etc, you would export (share) your movie to your desktop as a movie file, and from there drag it into a DVD authoring program (or otherwise follow the program's instructions) to import the movie into it. Apple's iDVD program has been discontinued and, in any event, will not work on Catalina or Big Sur 64 bit operating systems. You can get from the app store an authoring program by peng Guiping called DVD Creator that some users on this forum have tried with success. You would then need some standard DVD-r discs and an external DVD burner (if your computer does not have an internal burner). Burn at 4x speed. A standard DVD disc will hold up to 2 hours duration of video.

On the other hand, if you just want to store your movie on a data DVD that plays on a computer but not all DVD players, you can use your Mac's burn program to burn to a DVD disc. In the Finder help menu, type "Burn CD or DVD" for instructions. A data DVD has no themes or menus, so it would be like you were storing your Movie on a thumb drive or other external drive. Because the data DVD does not compress the movie like an authoring DVD would, you are limited to about 4GB in size.

-- Rich

At first, you should export videos from iMovie, and then burn iMovie videos to DVD with a DVD burning program. If you want to use a free app, try Burn, which creates DVD or CD from data, video, and audio. But it lacks DVD template customization options. To make a stylish DVD menu and burn fast, try more professional software, like Cisdem DVD Burner.

Glad that I could help. 😊

— Rich