It certainly exists. Whether you have it installer or not is a different question.
All fonts used in Indesign must be enabled in your computer (PC or Mac). Try installing the fonts you need and try again.
You know Arial italic and Arial Narrow italic are two real different fonts. As Arial Bold is not a thickened Arial, but a real typeface designed as such. Fonts installed in the operating system are readily available to InDesign and other apps.
If you are in Windows open that folder and the Fonts subfolder where you will find the Arial family members installed.
Check on the Control bar window if both are installed. I f you have opened a document and a typeface appears between [ ] , it means the font is not installed, it's used on the document.
I have it already, and I am not sure I have it installed. very likely it was installed by Windows 10 in my case. I do not think InDesign includes it