Bukhari

Hadith Commentary:
Imam Nawawi rahimahullah states:
Ibn Abd al-Barr said: “Consensus (ijma‘) was later established upon four [takbirs], and the jurists and the people of fatwa in the cities are unanimously agreed upon four, as has come in the authentic hadiths, and anything besides this, according to them, is an oddity to which no attention is paid.”
(Nawawi)
That is, Ibn Abd al-Barr said that all the jurists and the people of fatwa have reached consensus on four takbirs, as has come in the authentic hadiths, and anything contrary to this is among the rare opinions to which attention cannot be given.

Shaykh al-Hadith Mawlana Ubaidullah Mubarakpuri rahimahullah states:
“And the preferred view according to me is that it is not appropriate to add to four; because in this is an exit from disagreement, and because that is what is predominant from the actions of the Prophet (sallallahu alayhi wa sallam). However, if the imam says five takbirs, the followers should follow him; because the establishment of five is also proven in terms of narration and practice, etc., and there is no room for its denial.”
(Mir‘at, vol. 2, p. 477)
That is, according to me, the preferred view is that there should not be more than four takbirs.
This is the way to avoid disagreement, and this is what is mostly established from the actions of the Noble Prophet (sallallahu alayhi wa sallam).
However, if the imam says five takbirs, the followers should follow him.
Because, in terms of narration and practice, the establishment of five is also proven, and there is no room for its denial.