I think you will have to remove the front bumper. When I did this on my old 2008 S80 (to fix a leak from the washer bottle) I used instructions from
https://www.drive2.ru/l/6570411/ and
https://accessories.volvocars.com/In.../S80(07-)/2008.
In my case the hose from the bottle to the headlight washer was busted.
Good luck.