The battery is the same as the 4 banger Accord, TSX, etc, the 51R.The basics are easy and don't require any special tools. I've Changed the drive unit's oil and it was very easy to do. Recently my 12V battery went dead with no warning and that was a real pain since no local stores carry the 12V battery and Tesla had to replace it but it was only 140$. Also when you put the car into service mode you can activate the abs pump for the brake fluid flush.
Our 2018 Model 3 warned us to replace well in advance of failure; Tesla came out and replaced it.