Not with the usual SmartThings presence indicator methods–their detection zones are too broad. The smallest is the zigbee SmartThings branded arrival sensor, and even that is about a 50 foot radius around the hub. So way more than just one room.
This concept, locating a specific person in one specific room is called micro location. Everybody wants to do it, but the technology just isn’t quite there yet.
There are some different methods that can sort of do it, but they involve carrying a device and checking in and out as you go through rooms. And often many additional devices and a lot of custom technical work.
Kristopher Has one that probably comes closest:
You can also do something with iBeacons, which can be set to a much smaller range. There are two problems with this approach, though. First, you still have to carry a device with you (either your phone or a Beacon depending on how you’re setting it up) and because these are Bluetooth devices they are not stopped by walls. Or floors. Or ceilings. So even if you set it to say a 6 foot range, it might detect you on the opposite side of the wall as well.
I personally do have a beacon attached to my wheelchair and I set the detection range to quite small, around 6 feet, so it will pick me up just as I get to the base of the wheelchair ramp that goes to my front door. And I have one other place in the house where Detects that I have entered (and not someone else). It works well for my own purposes, but then I’m not going anywhere without the wheelchair so it’s pretty easy to have a device attached to that.
To keep from getting too far off topic, we should probably take additional discussion of microlocation to the following thread: