That's a very general Gide, isn't that 16m2?. There are factors in a room that can make a huge difference . like north/ south side of the house, windows, insulation, ceiling height, concrete floor, walls facing outside or to adjacent room.
We all have experienced homes that have a room you could bake bread in (everything working against it) and other rooms that have everything in there favor (bordering on actually needing any artafical cooling even on the hottest of days)
In Qld ist often a case of not a lot of heat load but the need to dry the air out ( 30c day that feels like 45c because the air is soking wet)
Like you say dig deeper and do a thermal load analysis on the room and get the correct unit (they last long time so it's worth getting it correct)
I visited a few online calculaters one was very in depth and had a lot of questions and measuments and materials that needed to be entered but it was worth the effort to fill it all in.
Offgrid 2008, Selectronic PS1 6kw/48v inverter, x 2 Midnite solar classic 150 MPPT, 3960w NE PV 24 x 165w BP panels, 4200w NW PV 21 x 200w DAQO PV, 16x400ah lithium.