Can you explain how to identify a preceding direct object (PDO) and explain what needs to be taken into account?

A preceding direct object (PDO):is a noun that is the direct object (DO) of the verb. *learning point: how to identify the direct object. syntactically comes before the verb in the sentence.is nearly always followed by 'que'.
For example: Le chien que j'ai acheté. 'The dog' is the PDO because its the direct object of the verb 'to buy'. It comes before the verb and it is followed by que.
What needs to be taken into account? Gender agreements. The verb must agree with the PDO, even when with 'avoir (= to have)'
Can you give an example of a verb agreeing with a PDO?La maison que j'ai achetée.