I replicate this in RB with minor differences. Rather than split the track, highlight the area you want to affect.

1. Rt click on the track and from the drop down menu select: Audio Effects... \ Gain Change

2. There are presets for boosts and cuts or you can manually set the parameters


BIAB 2025:RB 2025, Latest builds: Dell Optiplex 7040 Desktop; Windows-10-64 bit, Intel Core i7-6700 3.4GHz CPU and 16 GB Ram Memory.