How can I give edit access to the records through role hierarchy.

Hi,

If your org wide default sharing setting for the object is Private, then if a user is above the owner in the role hierarchy AND they have edit access on the object through their profile or permission set, they will be able to edit the records.

If they are below the owner in the hierarchy, you would need to create sharing rules. However, they will ALWAYS need to have edit access on the object through their profile or permission set