The std oil volume is 454 ml and the std oil height is 100 mm. You should use the volume value as a guide and adjust it to set the oil level with the forks fully compressed and the spring removed. The oil level range is 80 to 120 mm and the manual shows that it takes 5ml of oil to change the oil height by 5mm. Again go by the oil height, not the volume.
You can buy a oil level gauge or what I use is a couple of zip ties hooked together to form a “T” shape. Trim one to about 2-3 inches and the other to about 4 inches. Slide the long end into the tube and let it rest on the short one. You may have to trim it more but don’t make it any shorter than 130 mm. Pull it back out and measure from the short zip tie to the point where the oil is on the long one. That is the oil height. You can remove oil by putting a straw or piece of tubing into the oil, hold the end of the tubing with your thumb and pull it out. Release the trapped oil by removing your thumb from the tube.