You’ll learn along the way.
The important part is being willing to work on a feature that would benefit a lot of people. Having a simple way to duplicate a post/page/custom post by using the quick edit bar would be really nice.
The process as I have noticed it is kinda like so:
A developer suggests a plugin or project they are working on as a feature plugin for core.
A chat is held in regards to possible feature plugins. There is a chat Tuesday next week. https://make.www.ads-software.com/core/ (check the right sidebar info for chat info)
A developer follows along receives feedback, answers possible questions etc.
Makes some changes to the plugin to create a better fit for Core.
And the plugin matures along the way…
Your plugin is small and does not require so much making it an easier project to bring into core. But it is up to the core developers to say yes or no to each project and if they say yes they can also give requirements (depends on complexity of project) and a timeframe. If they say no that it does not fit into Core then the project will likely turn into a plugin that people can install on their own. (Your plugin is small and does not create a large footprint). It is interesting taking part in the process finding out various features that might make it into core.