There are hundreds of pee-reviewed papers examining the link between vaccines and whatever diseases they're supposed to magically cause.
I make it a point not to argue with anti-vaxxers, anti-evolutionists, flat earthers, climate change deniers, or any such rabble. Because I think if you're there, then you either have serious inability to meaningfully weigh information, or you just don't give two ****s about the facts.
But I'll make an exception. The reason children are given more vaccines is because as science has advanced, it has become possible to immunize against more and more diseases while using fewer and fewer antigens. For example, the full vaccine schedule in the 2010s exposes the body to fewer than 200 antigens. The WC-Pertussis vaccine from the 80s had 3000 antigens on its own. So current vaccines are safer, better targeted, milder, and more effective, which enables doctors to introduce more vaccines at a younger age. In fact, an infant's body is exposed to far more pathogens from the environment on daily basis than they would from all the vaccines combined.
The reality of the situation is easy to research and study if you were making an honest effort to understand the situation. Instead of listening to the concerns someone on Youtube has, and that happen to fit with how you want things to be.