2023.2 renders coming out blurry at the highest path tracer settings

It feels like I've tried everything and watched every Youtube video on the subject. Any ideas why I'm getting such low quality path tracer renderings, even with the highest settings enabled? I have RTX 3070 and 64 Gb RAM.

Ok, I may have just answered my own question. I have been attempting to render an entirely interior scene- ie no windows. So I modeled a black box around my scene in Rhino, thinking that I needed to ensure no environmental light seeped in. Turns out that even though my rendering scene is totally enclosed in geometry, I still need to turn on an HDRI skydome to get clarity.

In case anyone has any other tips for a new TM user, I'd appreciate any general rules of thumbs, or preferred settings for interior renders.

Thank you.