At least 1.5 kg if 2kg plane...
If the plane weighs 2kg and thrust is 1.5 kg then how can the plane fly ? For this get a low kv motor swinging a big prop.
Regards
I can comfortably take-off, fly and land a model weighing 2 kg with a power unit producing 1.2 Kg thrust
Just go back to basics - lift is not the same as thrust. If you want to climb vertically, only then thrust > weight
That said, do not underpower! Always safer to have thrust:weight around 1 for trainers, 1:1.2~1.5 for sports models, and 1> 2 for 3D models