"I think Full-time job can not get 1099-NEC form employer like a hospital."
Full time and Job don't really go together in creating a limitation or restriction as you stated it. Amount of work (full time or not) doesn't have anything to do with Payroll (W2) or not (1099-NEC). 1099-NEC is not a synonym to W2. It identifies a different relationship.
A Job as Employee of an employer, means payroll and W2. A Job as Employee of an S Corp, means payroll and W2, even if you own 100% of the shares. W2 is the form issued to employees (who submitted W4 and I9 for employment), who are paid through payroll. They work for a company that provides for their tools, assignments, schedules, and supervision. A Shareholder-Employee is wearing two hats, in other words (they might be their own boss). The Supreme Court ruled that Corporations are people, too. That's why the shareholder working for the S corp also is an employee, because some human must "do the work" of that business on behalf of the corporation.
1099-NEC is issued to people who are not the employee of the party to whom they are providing their services, which is why you use the term Independent Contractor (and they submit W9 for tax identification purposes) when the labor or service is between two companies. They are contracted by one party to provide their business expertise as a separate entity to the customer contracting with them. An independent contractor carries all the risk of their work, has to keep up with their profession (licensing, instructions, E&O and liability and other insurance), uses their own tools, works without supervision, sets their own schedule.
Since 1099 is an informational form, there is no requirement to issue a 1099-NEC to an S Corp, and it makes sense if you keep in mind S Corps are supposed to be running everything through payroll via reasonable compensation, so that means all of this is revealed anyway, through 941/944, 940, W4, W2, and other filings. But, there are some requirements to issue 1099-NEC and 1099-Misc, even to corporations, such as for medical services, rent, and other reasons.
"can he form S-Corp?"
Sure, But you have to know why, and this is not a tax saving strategy. It's an operational concept. It doesn't replace the employer for work being done, if the worker classification is already correct. In fact, it is sometimes asked that an employee should form an LLC or S Corp so the employer can drop them as an employee, for fraudulent reasons. That's worker misclassification.
For instance, locally, our ambulances outside the hospital emergency entries are a contract service. It's outsourced, in other words. The hospital does not provide any equipment, but the ambulance service is on site. The lease of the space is included in their contract.
If he works for the one hospital as an employee, but also has his own clinical practice or has his own research contracts/grants, then the nonemployee activities might be contracted, and he would contract under his S Corp (not replacing his W2 position, but supplementing with these other services and sources of income). And if he does that not through an S Corp, but perhaps an LLC or PLLC, he gets a 1099-NEC. If he does that through the S Corp, he is acting as President of the S Corp, signing a contract for services with a customer (or grantor), then he hires his employee (himself) to do that work, and that means the research facility activity or clinic pays the S Corp, the S Corp has him on payroll, and he still gets a W2, but for the work not from the hospital. So, he gets two W2.
There can be strategies to help reduce tax burden from a personal financial perspective, but when you make a lot of money, you end up paying a lot in taxes (for the most part) and that's the point. Incorporation isn't a tax strategy. It shifts the burden, and sometimes makes things worse.
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