If you're asking about the appeal just filed to SCOTUS following the 6th Circuit's lifting of the STAY on the enforcement of the OSHA vaxx-or-test mandate for companies with 100 or more employees, then all they are ruling on (if they accept the appeal) is whether the STAY should be in place (which indicates a likelihood that those asking for the stay will be successful below on the merits).
The OSHA mandate challenge itself - on the merits - is underway in lower courts.
If the STAY fails at SCOTUS level, people worrking for companies w/100 or more employees can either take the jab OR test every 7 days and mask at work - while the challenges to the merits (not just the stay) work their way through the courts.
A link to the appeal (regarding the 6th Circuit's lifting of the STAY of the enforcement of the OSHA vaxx-or-test mandate for companies with 100+ employees) to SCOTUS is at the end of this article:
https://www.live5news.com/2021/12/18/sc-attorney-general-files-appeal-osha-vaccine-mandate-ruling-with-supreme-court/
Summary: There is no scenario in this case where SCOTUS would say you must get the vaxx (without the "or mask and test" option) and it is limited to companies that employ 100 or more.