The EIC is based on several factors such as age, earned income, adjusted gross income, filing status, whether the taxpayer had no qualifying child, had one qualifying child, or had two or more qualifying children, etc.
The EIC worksheets and tables can be accessed on IRS Instruction 1040 1040 and 1040-SR Instructions, pages 46-56.
You can view the EIC checklist and tables on IRS Publication 596 Earned Income Credit (EIC), pages 30-39.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the webpage or document at the time it is accessed.