Not being plagued with arthritic knees I have a limited view on what that means. Squats are essentially standing up from a seated position, only without a chair and with additional weight sitting on your shoulders. Start doing squats with a chair and no weight. Then add some weight and keep the chair as a stop so you don't inadvertently go too deep.

If arthritis is affecting your flexibility -- I don't have the flexibility I once had so when I'm doing squats and move to the seated position, I probably don't go low enough to be legal per competion rules; I don't care, I'm not competing. I take it down to where my knees don't hurt and call it good enough. Some of the younger guys do deep squats with weight and I have to shake my head thinking what their knees will be like in later years. Maybe they need to train for a deep squat but I don't know why.

Squats are full body but at a point there is too much risk and limited gain. There are a lot of muscles engaged and working together when you do a squat. You don't need to go all the way down to get the benefit.

Just my amateur opinion.