When you ask about the need to certify to ISO 45001 you could mean one of two things, so I will answer both questions:
First, the ISO 45001:2018 standard has the option to either certify your OHSMS with an external organization, or to self-determine and self-declare conformance to the standard by the company. This could then be confirmed by interested parties or others; this is all captured in section 0.5, Contents of this document. What this means is that you can use the ISO 45001 requirements to implement an OHSMS at your organization, and then declare that you meet the requirements without having a third-party certification body audit your organization; you could not use the term certified though with self-declaration.
Second, if you are asking if there is a requirement to implement the ISO 45001 standard and create an OHSMS at your company, then this is something that you need to verify with your customer and legal requirements. If you have a customer or legal entity demanding this, then implementation is something you will need to do. ISO itself has no legal authority to impose these requirements on an organization, so you will need to verify your own industry, customer and legal requirements.