Through increased breakdown, the body cleans out the damaged parts of muscle fibers, and through synthesis it repairs them or grows them anew.
The body simply repairs what has been broken, and this has no effect on the formation of new muscle fibers.
Don’t judge the quality of your workout by the amount of soreness. If you have no pain, it doesn’t mean that you didn’t train well and your results will stand still. It is better to be guided by the volume and weight increase in strength exercises.