To make things clear the ender 3 standard software Cura set the height of the nozzle for the initial layers as 0.3mm to which must be added the height that nozzle was set above the bed I recommend 0.05 to 0.75mm (0.002 to 0.003 inches) so the actual distance is just under 0.4 for the first layer, the firmware will compensate by over extruding to get the slightly squished down appearance shown in Roberts wideo.