UPGRADE 500 SSD HD TO 2 OR 4 TB SSD Macbook Pro 2018

G'day from Australia all, my question is am I able to replace my 500 SSD internal HD to a much larger 1,2 or 4 TB SSD HD its a 2018 15 inch Macbook Pro, I have had mixed reports and was told that this model had the SSD HD attached to the motherboard and can not be removed up up graded, is this true ? Thanks for your help.