This was announced by the Vatican Press Office on Wednesday as usual without further details.
Zen is in Rome on the occasion of a meeting of all the cardinals with the pope, which ends on Thursday evening.
The extraordinary consistory will discuss questions of the future of the Catholic Church.
The former archbishop of Hong Kong had distinguished himself in recent years as a critic of Vatican China policy as well as an opponent of internal church reforms.
In 2023, together with four other cardinals, he sent a list of critical questions to the then Pope Francis.
Proponents of the "Old Mass"
Among other things, it was a question of whether more co-determination in the Church is permissible and a more liberal attitude towards homosexual couples is compatible with church teaching.
In addition, Zen repeatedly expressed himself as a proponent of the "Old Mass" and condemned the restrictions on this form of liturgy by Pope Francis.
The Vatican's China policy, which under Francis sought an understanding between the state and the church in the appointment of bishops, sharply criticized Zen.
He supported the protests of democratic forces in Hong Kong against the Communist leadership in Beijing and was briefly arrested for it in May 2022.