Anisa Dhana builds a sample flowchart with DiagrammeR:
After some search, I found that there are a few packages in R which allow making exemplary flowcharts. The one which I found easy to use was DiagrammeR. The advantage of this packages is that generate diagrams using code within R Markdown syntax.
The taped-glasses nerd in me wants to point out that flow charts use geometric shapes to show flow and that this is more properly labeled a graph (the examples are directed acyclic graphs), but hush, taped-glasses nerd self.