Sales are dropping because wages have barely outpaced inflation for the last 30 years and expenses like college, housing, and medical care have all greatly exceeded inflation over the same time. There's less disposable income for most people now than in the past. Lenders are doing 7 and 8 year loans on depreciating assets because it's the only way most people can afford a new vehicle, and taking those kinds of loans only makes the issue worse for the consumer. Also, new vehicles are lasting longer than ever. The average age of vehicles on the road goes up every year and is something like 11 or 12 years old now. People can't afford new vehicles on a whim, and there's nothing forcing them to buy them since their 10 year old car is generally reliable and not rusted away to nothing.
EVs don't have anything to do with selling more vehicles. In fact, with the fact that there are fewer components, and they're generally more reliable than ICEs, in theory adoption of EVs should lead to fewer new vehicles being purchased out of need. This is why automakers are dumping so much money into other "mobility" services. That's how they keep their revenue going in the future where cars aren't sold as often.