What is the ruling on reciting loudly or softly for one who missed part of the congregational prayer and stands to complete the remainder?

Primary text

The ruling for one who missed part of the Maghrib or Isha prayer with the Imam and stands to complete the remainder is that they are given a choice: they may recite loudly or softly. This is explicitly stated by Ahmad concerning one who missed a rak'ah of Maghrib or Isha and then stood up for make-up. This ruling is governed by the same principle applied to the sole worshipper, as the defining characteristic of obligatory loud recitation pertains to the congregation as a whole.