are you asking about regular losses or QBI loss carryover? Generally, it's unusual for a sole proprietorship to have regular loss carryovers because business losses would be applied against other income. If adjusted gross income is negative that loss becomes a Net Operating Loss not reported on schedule C. Passive losses when you are the only one involved (except real estate rental which would normally be on schedule E) seem illogical. Loss suspension due to at-risk limitations also seems illogical. so what I suggesting is that if a regular loss carryforward you're talking about, something may have been done wrong in a prior return. However, it's entirely possible to have a QBI loss carryover - different rules. That loss c/o is a forever carryover unless the law changes.
