This is a regular verb. It follows the conjugation pattern of the verb falar.
Present:
A Clara manifesta a opinião dela com calma.
A Clara manifesta a sua opinião com calma.
Clara expresses her opinion calmly.
Imperfect:
O Miguel manifestava dúvidas sobre o plano.
Miguel used to express doubt about the plan.
Future:
A Ana manifestará apoio ao projeto.
Ana will express support for the project.