Perspective starts with two arbitrary decisions. Everything else is carved in stone. I've decided: 1- it's an "average" American tract home; 2- the furniture is store bought (not custom made by, or for, hobbits and giants)
Blue - Project the top of the window back to the horizon. Where the projection crosses the room's corner vertical is 80" (6'8") off the ground because doors and windows share common header height if not common headers. Split heights in half repeatedly to mark 40"-60"-70" etc. We can now estimate the height of the 8' ceiling and scale the room.
Red - Drop a vertical for the center line of Mr Red. Project an horizontal from the base of the cabinet. That's the base of Mr Red standing next to the cabinet. Project from the base of Mr Red to anywhere on the horizon. Where the projection hits the floor line, raise a vertical. Using the scale, project a height of 69" (5'9", average American male) along the wall. From Mr Red's VP, project a line through the wall vert at 69" back to Mr Red's center line. We now have the height of Mr Red and can approximate a 48" tall chest. Your cabinet could be an armoire but, it's too tall to be a chest of drawers. There are grownups shorter than 5' and a store bought chest will allow them access to the top drawer.
Green - Let's say Emerald Boy is 12 years old and, normally, comes up to the chest of Mr Red. Bent over, he'll come to Mr Red's navel. Project from EB's base through the base of Mr Red to the horizon. From there, through Mr Red's navel back to EB. Your EB is the size of a toddler.
Gold - Let's say EB and Golden Lad are the same height. GL loses 1.5 heads from sitting down. EB loses 1 head from leaning over. Project from EB's base, through GL's base, to the horizon. Project from the horizon back to the mid point of EB's head. GL's head will top out along that 2nd projection. We see that Golden Lad has easy access to the platform of screaming, squishy death.