I need it to do one thing when I'm using it like an .Rmd without output to the RStudio notebook, and another when I'm rendering to produce a final .html file. But, from your second link, maybe this just isn't how Quatro is designed to work? If I want to work interactivly on a project, then publish a final html, is that not something that Quatro can do?
I did originally raise this on the IDE group here but it seems it got moved over here. Maybe someone with authority could move it back again if you think it's a question for the IDE folks?
You should be able to run interactively the chunk. I am just not sure you can control the plot size using knitr options.
If there are respected with Rmd document, and not Quarto (qmd), then I would open an issue with examples in the RStudio IDE github repo for missing feature.