The system can take either battery, so it will auto-adjust.  Any installation is up to you (or you will need to hire a shop to do the work);  Dell does not cover post-purchase upgrades.  
I've a DELL G15 5525 Ryzen 5 6600H RTX3050 laptop with a 56WHr battery pack. At this moment the battery is just sufficient for me, and I have to take my laptop to my college every day and surely after some time as the battery health with decline and my battery will degrade, I will stop getting enough battery backup to meet my daily day to day needs. So, I am thinking to get my battery replaced with 86Whr one which comes standard with the higher, more expensive models of the same G15 lineup. So, I want to know if it's even possible to put 86Whr battery in place of my standard 56Whr battery in the G15 5525 model.  
Dell G15 5525 battery upgrade