a rug

We call that rough in for a toilet why are you doing the new flooring there at all. IMO a rug might work depending oon where that is in the space so a btter pic showing exactly where that is for sure . Post the new pics in a comment here do not start another post

It is not a rough in for a toilet, it is right next to the door of the basement

This may show a little better. A rug is my backup option, thank you for taking the time to respond!

I'd see if they make caps like that out of a nice metal that coordinates with your room. Something that is flush with the floor so it is not a tripping hazard and is just a shiney metal disc on your floor. There is no getting around the fact that this is a basement but you can make the cover look nice instead of just ultilitarian.

Easy low-cost option: Take a scrap of flooring to home center and buy spray paint to match in a matte finish. Spray the sewer cover. If it still bothers you, cover with a rug, but it may just blend in with the floor.

Or just cover it and carefully note where and what it is for yourself and future owners.

Cut in a magnetic customizable brass plaque from customesigns.com?

Probably should not be filled with what looks like concrete.

I like the north/east/west/sewer solution.

It's a sewer cleanout. I have some brass ones in the shop that look nicer than this - but agree you can cover it if you want - just remembering that the flooring may need to come up if you need access. I would think that a nice brass cover would suffice. Or - as noted - paint it. You could also fil it with auto body filler to cover the SEWER callout and then paint it.

I'd first determine the use of this sewer pipe. Another comment noted that it is filled with concete. Is that accurate? If this is an old pipe that is no longer used and cannot be used for anything then can you just put the flooring over it? Maybe note where it is so in case anyone needs to know for the future you have a map to get to it.