What is it at now? Why do you want it higher? Tank parameters? Occupants? Age of tank? Maintenance routine?
The short and sweet--yes, you can add things to increase pH. Some commercial products are bunk, some work great. The bigger issue--and the reason for the other questions--is that for most community fish, a stable pH is much more important than a specific pH. Efforts to modify your water require lots of attention--it will seldom be as simple as a one time additive fix, but rather frequent monitoring and tweaking. Without care, you can cause yo-yoing values, which are much more stressful for the occupants than a pH that is lower than 'ideal'.