The Imam should make the prayer short
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، أَنَّ النَّبِيَّ صلى الله عليه وسلم كَانَ أَخَفَّ النَّاسِ صَلاَةً فِي تَمَامٍ .
It was narrated from Anas that the Prophet (ﷺ) used to make his prayer very brief but still complete when leading people.