Imam And Congregation Offering Du‘aa’ Together Following Jumu‘ah & other Prayers

Question
We pray the two fard rak‘ahs of Jumu‘ah, then after
that the imam turns around and we all offer du‘aa’
together. Is what we do correct?
Answer
Praise be to Allah.
What the believers should do is follow the example
of the Prophet (blessings and peace of Allah be upon
him) with regard to what he did and did not do. He
should do what the Messenger (blessings and peace
of Allah be upon him) did and refrain from that from
which the Messenger (blessings and peace of Allah
be upon him) refrained. Allah, may He be exalted,
said (interpretation of the meaning):
“Indeed in the Messenger of Allah (Muhammad
SAW) you have a good example to follow for him
who hopes in (the Meeting with) Allah and the
Last Day ...”
[al-Ahzaab 33:21].
Du‘aa’ by the imam after an obligatory prayer –
Jumu‘ah or otherwise – with the congregation
saying Ameen is something that was not done by the
Messenger (blessings and peace of Allah be upon
him) or by any of his Companions (may Allah be
pleased with them). If it was good, they would have
done it before us.
Based on that, this action comes under the heading of
reprehensible innovation.
The Prophet (blessings
and peace of Allah be upon him) said: “Whoever
among you lives after I am gone will see great
disputes; you must adhere to my Sunnah and the
way of the Rightly Guided Caliphs. Hold on to it
and cling fast to it. And beware of newly-
invented matters, for every newly-invented
matter is an innovation and every innovation is a
going astray.”
Narrated by Abu Dawood, 4607; classed as saheeh
by al-Albaani in Saheeh Abi Dawood.
And the Prophet (blessings and peace of Allah be
upon him) said: “Whoever introduces something
into this matter of ours that is not part of it will
have it rejected.
”
Narrated by al-Bukhaari, 2697; Muslim, 1718.
Ash-Shaatibi (may Allah have mercy on him)
mentioned congregational du‘aa’ after the obligatory
prayer in his book al-I‘tisaam (1/349-355), and
explained that this is an innovation, because that was
not done by the Messenger (blessings and peace of
Allah be upon him) or by any of his Companions
(may Allah be pleased with them) or any of the
imams (leading scholars) after them.
What you must do is refrain from this innovation
and strive to recite the adhkaar and du‘aa’s that
the Prophet (blessings and peace of Allah be upon
him) used to say after the prayer. And whoever
wants to offer du‘aa’ may do so quietly.
And Allah knows best.

https://islamqa.info/en/answers/115781/imam-and-congregation-offering-duaa-together-following-jumuah-prayer