You bet. If you just want to adjust the overall volume of an instrument across its entire track, you’ll find each instrument’s volume slider under the MIDI menu / MIDI Options.
If you’re wanting to adjust the volume of an instrument for a small section, go to that instrument’s page and highlight the notes in the section where you want to adjust the volume. Right click on the highlighted section and choose Dynamics. In the Dynamics window, “fff” is the loudest with each subsequent entry getting quieter. I’ve found anything below “p” (which I understand means “piano”) is too quiet to even hear, and I haven’t messed with anything softer than “mf” (mezzo forte) in that list.
Hope I answered your question.