In fact your question could be summarized as : should I use a mono-repo approach or a multi-repo approach ?
That is broad subject but to make things simple: it depends on the coupling level and the life cycle between these projects.
You want to use a mono repo approach and add multiple projects in if these projects are designed to live and evolve together. For example, if only these projects have dependency between them and that when you change a dependency you will change the consumer, you have clearly no value to split out them in multiple repositories.
It will make global source code readability weaker and commit/pull/request/merge on multiple repositories for a same use case, which makes their readability and their consistence weaker.
You want to use a multi-repo approach and to have a project by repo in if these projects are not designed to live and evolve together. For example, if some of these projects are used by other applications than those you quote, you have no value to couple the project dependency inside the repository of the consumer project because there are other consumers, so why that consumer and not the other one ?
You have also the super mono repo approach such as that one used by Google or Facebook that adds all projects (or almost) in the same repository, whatever the level of coupling between projects.
Doing such a thing is not simple and demands to custom finely the CDCI and the SCM tools to keep things practical and simple in spit of the repo size.