Yes, but  a child's disability doesn't affect tax filing until he turns 19 (24 if a full time student). Then his disability allows him to continue to be considered a "Qualifying Child" for tax purposes regardless of age. There are no additional credits or deductions, for being disabled, other than that some items, e.g. special schooling, can be considered medical expenses.

If qualifed, you may claim your child as dependent,  Under your child's information, there is a question in Turbo Tax, "Did any of these apply to the child"?, choose the bullet "was disabled".  

In order to claim a disabled child, although age is not a requirement,  a child must be permanently and totally disabled based on doctor's certification.  If qualified, you may receive child tax credit and earned income tax credit on your income tax return.

[edited 3/2/2021 @ 2;47PM]

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@Hal_Al wrote:

Yes, but  a child's disability doesn't affect tax filing until he turns 19 (24 if a full time student). Then his disability allows him to continue to be considered a "Qualifying Child" for tax purposes regardless of age. There are no additional credits or deductions, for being disabled, other than that some items, e.g. special schooling, can be considered medical expenses.

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If a disabled child can't take care of himself and requires day care so that the parents can work, the child qualifies for the child and dependent care credit, even if they are age 13 and older (when non-disabled children no longer qualify for that credit.)

Also, "disabled" for tax purposes means "unable to perform substantial gainful work".  Many people who meet a medical definition of disability can perform gainful work and are not disabled for tax purposes.  Hopefully your son will be able to manage his issues and perform some kind of employment when he gets older.

Bottom line, of course, is that checking the "disabled" box for your dependent doesn't actually do anything on your tax return until he turns 13 at the earliest.