I have a 106" screen paired with a JVC NP5 (last bulb based native 4k projector they made) with an MLP of somewhere in the 11' - 12' range. I also recently set up an 85" Samsung QN90F at my folk's place. A fairly different room but I'd estimate the seating distance is roughly in the same range there as well.
I bought the NP5 about a few years ago. 98" TVs were just starting to show up in more affordable price ranges (~10k CAD, similar to the projector's price). Like you, I wasn't sure I could get a TV that size into my basement (I think it might be possible but it would be an ordeal) and that generation of nearly affordable 98" TVs were not on the same spec level as the smaller ones. So, like you, it was also a choice between projector and 85" panel at the time.
You're talking 85", so I'm going to assume that you mean LCD of some sort rather than OLED (as OLED would have to be 83" or 97"). The 85" TV will have black levels that match or best any projector. It will feature HDR highlights far, far beyond what a projector can do. It will be less sensitive to the room environment (IE, you don't need to light control it and all that to anywhere near the same extent). It will generally have less maintenance and care concerns.
By contrast, the projector might be slightly more uniform in terms of visible bloom (depends on the models, room and partly a function of "bloom" on a projector tending to be a room effect and larger/less obvious on a screen than what you get on an LCD panel). It will also be ~55% larger in actual viewing area. The diagonal difference might not sound like that much but it ends up being a bigger difference than you might think. The projector screen also offers you the option of doing transparent screen or automatic matting for aspect ratios if you go really fancy but I'm guessing that's not in the cards here anyways. I will say that my experience is that, when it comes to UHD, being limited to 300 nits or less on a projector is less of an issue that you might think if you have good tonemapping because the sheer size of the highlights helps make them seem brighter anyways. That is to say that I enjoy the HDR presentation on mine just fine while actually watching, even though if I go sample the same content on a panel afterwards, the difference in brightness is obvious then.
You'll note that I didn't actually say that the TV is the obvious choice. Because it isn't. No one will really be able to answer this question for you because, ultimately, you have to decide if you favor the better technical picture from a good panel or if it's simply the big screen effect that you prize most. They're both valid aspects to favor as your preference if you're forced to prioritize one. An 85" panel at that viewing range won't be small and will do a good job, but won't be the same as the 100+ inch screen effect.
In my case, I went with a new projector. It was more convenient to just replace the existing projector rather than sort out the room a new large format panel (this is partly due to the nature of the half wall around my room). I also have a 65" UHD LCD panel down there (the screen for the projector drops in front of it when in use) and a 65" OLED in another room - so I have other options for viewing in different presentations. For me, I decided to keep the larger format viewing experience option. I discovered afterwards that light and reflection control was more of an issue with HDR content so I ended up having to do a bunch of extra treatment stuff in that room but I already had the projector so I was sort of already committed in that sense anyways.
I suspect that you're going to have to weigh some of things for yourself. How you come down on them should steer your answer and choice.
