She has to discuss this with her employer. There is nothing she can do at tax filing time to make that change on her own initiative.
That said, something isn't right. It may just be that she needs to wait to if she gets a W-2 or a 1099-NEC. She simply can't be a W-2 employee AND be paying the employer share of FICA tax. Her pay stubs should be showing 6.2% social and 1.45% Medicare withholding. If none is being shown, then she is all but certain to be an independent contractor. A contractor should expect to be paid ~7% (.9235 x 7.65%) more to compensate for taxes.
