Laptop Ideapad Gaming 15ihu6

Planning to add another ssd on my laptop, lenovo tech support said its up to 1tb, but I already have a 2tb m.2 nvme that is supposed to be on my pc (my pc is already at 4tb), what would happen if i put that 2tb on the laptop. Also, how to know if my laptop can do flex mode, and if it is how much ram could I pack into it (its an 8gb, dont know if soldered, but just in case).