Do concert accompanists change the tempo depending on the dynamics of the singer?

If you're in a band or have a guitarist-pianist accompanying you, it's possible for the tempo to follow the song.

Accompaniment, a musical term for the instrumental music that accompanies and sets off the singing. Peking Opera singing accompaniment to the main instrument Jinghu-based, full-voiced full with the accompaniment. That is, the accompaniment is basically the same as the singing tune, during which there can also be a variety of decorative notes or high and low octave flip. The accompaniment must also play the purely instrumental parts to connect the singing phrases. Usually referred to as singing music is including the main instrument-based orchestra accompaniment.