Hello Alec,
Thank you for posting question on Microsoft Windows Forum!
Based on your query of Fine-Grained Password Policies (FGPP) vs Group Policy Object (GPO) for this specific task. Well! Active Directory has a strict rule regarding domain accounts. It only respects the password policy configured in a GPO linked to the Domain root (which is almost always the Default Domain Policy). If you create a new GPO with a stricter password policy and link it to an OU containing your admin or service accounts, AD will ignore it for those domain accounts. Instead, that OU-linked password GPO will only apply to the local accounts (the local SAM database) of any computer objects that happen to reside in that OU.
For Fine-Grained Password Policies, on the other hand, instead of relying on OU structure, FGPP utilizes Password Settings Objects (PSOs). These PSOs allow you to define completely different password requirements (length, complexity, history, and lockout settings) and apply them directly to specific Users or Global Security Groups. When a PSO is applied to a user or a group they belong to, it successfully overrides the Default Domain Policy for those specific accounts.
Therefore, for this specific task. You must use Fine-Grained Password Policies (FGPP). You cannot use a Group Policy Object (GPO) linked to an Organizational Unit (OU) to enforce a different password policy for domain user accounts.
You can consult the following article for configuring fine grained password policies..
Hope the above information is helpful! If it is. Free feel to hit "Accepted" for benefitting others in community having the same query too.