formalize
verb [ T ]
(UK also formalise) uk/ˈfɔːməlaɪz/ usto arrange something according to a fixed structure:
formalize a process/procedure/structure, etc. It is now widely acknowledged that with increasing size comes the need to formalize operations if a firm wishes to remain effective.
Despite the apparent contradiction, casual working in this sector is a highly formalized system of working.
to make something official:
formalize an agreement/arrangement/offer