Often, while doing a Review, I find projects disguised as tasks. In such cases, I use the command
Edit > Convert To Project. However, that command always creates projects at the root of the database.
So, I developed a Plug-In which creates new project inside the current folder. If the project is at the root, the new project is created after the current project.
Also, it brings that functionality to the mobile versions, since OmniFocus 4 iOS/iPadOS (beta) currently doesn’t have that it.
The Plug-In can be downloaded from my GitHub repository (it’s inside OmniFocus 3 & 4 folder):
Note: OmniFocus 4 is beta release software. As such, features could change without notice.