Explanation/Reference: https://automationchampion.com/tag/how-to-post-on-chatter-with-process-builder/

Explanation
The two actions that an app builder should take to meet the requirements are: Implement a sharing rule. A sharing rule is a way to grant additional access to records based on certain criteria, such as record owner, role, profile, or field value. The app builder can create a sharing rule that grants read access to all accounts with the VIP Account field value to all users. This way, all users can view these accounts, but only the owners can edit them. Change organization-wide defaults. Organization-wide defaults are the baseline level of access that users have to records they do not own. The app builder can change the organization-wide default for accounts from Public Read Only to Private. This way, only the owners can view and edit their own accounts, unless additional access is granted by other means, such as sharing rules. Configuring a permission set is not a valid action, as it does not affect record-level access. A permission set is a way to grant additional permissions and access settings to users on top of their profile settings, such as object permissions, field permissions, app permissions, etc. Setting up an Account Team is not a valid action, as it does not restrict record-level access.
An Account Team is a way to share an account and its related records with a group of users who work together on the account, such as sales reps, managers, or support agents. An Account Team grants additional access to team members based on predefined roles and access levels.