There is, generally, no direct legal requirement as such. Organisations choose whether or not to implement the requirements of ISO 27001 based upon the benefits that would be gained by doing so.
However, you should pay close attention to any contractual obligations you may have for protecting the information of clients and other stakeholders.
There is an increasing trend where customers require third party suppliers to implement or certify to ISO 27001, thus making it a legal requirement, by way of a contract.

ISO 27001:2022 - A.5 Organisational Controls (Access Management)
URM’s blog explores why the access controls in ISO 27001 matter, and how to implement each control in full conformance with both the Standard and best practice.
Read URM’s blog, where we explore the importance of clock synchronisation for cyber security and resilience, and how to meet the requirements of Control 8.17.
URM’s blog explores Clause 5.1 of ISO 27001, what you must do to meet its requirements, and why leadership & commitment are vital to an effective ISMS.
URM’s blog examines how ransomware occur, and highlights practical cyber security measures you can implement to reduce your exposure and mitigate security risk.

