Are there many people who are born professional singers without exercising?

Actually that's what singing is about. You just have the talent. (like many other professional talents)

And the word "Professional" is for every singer. Every singer can be professionals there's nothing special to it, all someone gotta do is to find the right path into the "professional world" then you become a professional.

Plus, nobody become a singer when they are clueless what is singing and then at some point in their lives they start to exercise then they become a giant singer. It can't happen. I speak this out with full assurance.

The practice is to improvement and to know how take your talent under control while you already have it. When to use and how to use it. How to get it effective and impressive.

You can not be a scientist your whole life and at the age 40 as a change of heart say "I'm gonna be a singer and i'm gonna be successful at this career" while you have no clue of "what is even singing" Noway.

Although we have the moment where many people discover their main born talent sometime late or pretty late.

Yet a talent must be within you from the first place and you start to realize the passion and capacity of improvement. Also you automatically get into it's path to learn more. About music, notes, chords, genres, voice types and it's professional roads, getting auditions, finding members, getting agents, contacting studio labels you'll just realize it how to go for it! Ect . . You'll have your clue and it's naturally with you. It never works to come in with no talent and try to "Exercise" out of the blue sky and then turn into a successful singer. That type of singing are for fun or a small career not an international mode.

From the Genetics you were born with, to the development of vocal cords, and lung capacity and diaphragm control as a child (being allowed to cry for a while in the crib to learn how to self sooth) . . . , the exposure to Harsh smoke or vapors that can deter proper growth in you the environment you grew up in and the food you ate . . .

All of things contribute to how you START and how you DEVELOPED physiologically throughout your early childhood to adulthood.  Exercising can help, but it helps to have the raw material in the beginning.