There are hundreds of publicly trusted Certificate Authorities and a subset of those implement a specification for certificate request/renewal called ACME (Automatic Certificate Management Environment) https://datatracker.ietf.org/doc/html/rfc8555 (ACME v2). Anyone can create (and use) a new certificate authority but only recognised CAs which can prove they follow strict issuance guidelines become generally trusted. You can, for instance, create your own ACME certificate authority and trust it within your organisation, but it won't be trusted by computers outside your organisation.