Hi,
What did you try exactly in your Rmd file ?
What is described in the topic you linked is the cause (Insert raw html iframe into RMarkdown - #7 by cderv)
You need to install the last dev version of knitr (which will 1.34 on CRAN very soon) to use knitr::include_url() so that it will add the correct attributes for you.
Using last dev version of knitr install from Github, this works for me.
---
title: Embeded URL
output: html_document
---
```{r}
knitr::include_url("https://cognitivewebpagestorage.blob.core.windows.net/wordpress-container/IPCVizFinal.html")
```
Next version will be on CRAN soon.