The room does not have one universal maximum
The biggest sensible television is the one that fits the viewing position, usable wall and installation conditions. Room area alone is a weak guide: two rooms with the same square footage can have very different sofa distances and wall layouts.
Set three limits before shopping
- Comfort limit: mock up the picture and check whether you can follow the whole image comfortably from the main seat.
- Space limit: allow for the outside cabinet, ventilation, soundbar, furniture and any mount movement.
- Installation limit: confirm the chosen TV and bracket can be supported by the actual wall.
A large screen that fits when flat against the wall may not swivel very far. Its edge can contact the wall before the bracket reaches its advertised angle. Check the TV width together with the mount's extension and installation position.
Think through delivery and lifting
Measure the doorway, stair turns and route to the room. Tell the installer about narrow access, upper floors and limited working space. Large panels can be awkward to handle even when their listed weight seems manageable. Follow the manufacturer's handling instructions and plan suitable lifting help.
When stepping down one size helps
A smaller TV can leave space for a lower, more comfortable position, accessible connectors and a properly placed soundbar. It may also let you use the type of bracket you actually want. The largest diagonal is a poor trade if you lose the ability to turn the TV or place it at a usable height.
For an example of very large equipment, see the documented Aptos installations. Those projects demonstrate completed configurations; they do not establish that the same mounting solution will suit another wall.