Use a tripod with a geared center column. Lower the center column, take the shot of the "floating" object(s). Raise the center column, remove whatever is supposed to "float", and take the shot that will be used for the background. Don't move the camera or tripod otherwise, and use studio strobes set up the same way for both shots for the lighting. If you have to use natural lighting, have a crew on hand to remove the couches or whatever between shots as quickly as possible. Lighting differences between composited elements is one of the easiest ways to spot a cut & paste job. Composite the shots in Photoshop.
Hope you are well and safe! Look after yourself.
Glad you can provide a solution so fast! In you method, to add 2 details. The central column needs to be lowered exactly the distance the people are meant to float above the floor. Also the lights have to be lowered that same distance so that thelight flux is that which would be at the effects virtual distance above the floor.