The US tax system is a "pay as you go" one.   If you underpay throughout the year, you can be subject to interest and penalties.  When you sign your W-4, you say [u]nder penalties of perjury, I declare that this certificate, to the best of my knowledge and belief, is true, correct, and complete.

2021 Form W-4 (irs.gov)

Further, if the IRS determines that an employee does not have enough withholding, it will notify the employer to increase the amount of withholding tax by issuing a "lock-in" letter that specifies the withholding arrangement permitted for the employee. 

There is an option to claim exemption from withholding.  However, you may claim exemption from withholding for 2021 only if you meet both of the following conditions: you had no federal income tax liability in 2020 and you expect to have no federal income tax liability in 2021.