Flexible work options may become a competitive advantage for some companies. Getty ImagesAmazon has announced a five-day return-to-office policy for corporate staff starting in January.Citigroup, JPMorgan, Goldman Sachs, and others have also enforced strict RTO mandates.Flexible work is likely to become a key recruitment perk, experts say.The list of companies abandoning remote work is growing.Last week, Amazon CEO Andy Jassy told corporate staffers that they would need to be in the office five days a week starting in January, up from the previous three-day policy.