VOD is a tough one.
1. Firstly, you cast as wide a net as possible meaning you make the movie available for purchase through as many services as possible in as many regions as possible.
2. You set the price on a case-by-case basis. So Disney set a a $30 price for Mulan (and tied it to their streaming service which isn't available in a lot of countries) but I think $30 is too much. Mulan is a Disney live action movie which would have undoubtedly done good business theatrically but it's not really a must-see movie that the masses would pay $30 for. I think $20 is more reasonable for it. Same thing with, for example, Dune. It might be a movie that audiences are curious about but it's not a must-see so $20 instead of $30. Now, MCU and DC movies, those you can put up for $30 or even $35. It's ironic that studios don't want to put the big comic book movies on VOD because those are probably the only movies that would be guaranteed successes on VOD if the studios want to stick to the $30 price point that is.
3. I have so far only talked about the purchase option but what about rental? Going with rental obviously has some benefits First, you might get some people to pay the $20-30 twice if they decide they want to see the movie again in a week or two. So repeat viewings basically. Second, making the initial release a rental allows you sell the movie to the same audience again later i.e. the home video market. On the other hand, less people are willing to pay $30 for rental. So then it comes down to whether you make more money by making your movie available for purchase immediately or you first make it available for rental (which will make less money comparatively) so you can double dip later.