As the leader of worship, it may be effective to lead the congregation to sing quietly, then to repeat the chorus or the next verse with vocal strength (louder).
A song that works well with dynamics is HOW GREAT IS OUR GOD. After the bridge, many worship leaders sing one or two times through the chorus very softly, then build it for a powerful (and vocally louder) repeat of the chorus for a big ending. Others, may choose to sing it loud, then bring it down for a more intimate time through the chorus.
If you have drums and bass (plus other instruments), the congregation will many times follow the instrumental energy level from loud to soft or soft to loud.
However, if you are the only instrumentalist, you may need to give vocal direction to the congregation. Simply insert a quick instruction to “sing it louder” or “sing it soft” or “quietly” as you begin the next chorus. Once you’ve sung the chorus softly, simply begin playing with more energy and confidently say to the congregation, “Sing it out!” “Lift your voices.” or what is comfortable for you.
Dynamics are always effective in worship, but so often we forget them.
Determine your plan for dynamics.
Communicate your plan to your instrumentalists.
Work your plan.
Don’t be afraid to lead. That is your responsibility.