Don't bother trying to adjust your pH without testing your hardness, as that will give you an indication of how easy it will be to adjust your pH. High pH and low hardness isn't uncommon for tap water as water companies prefer the water not to be acidic as it can cause problems for plumbing, and if this is the case then a bit of driftwood, or peat, or alder, or IAL can easily bring the pH down (in fact if the hardness is very low you may need some sort of mineral buffer to stop it going too far in the other direction). If you have high pH and high hardness (quite likely if you're in limestone country) then wood/IAL etc is hardly going to make a difference to your pH (and the hardness/conductivity is more what matters to your fish anyway, so it wouldn't help even if it did), and in that case the only real option is to use RO or rain water, which can be mixed with tap water to get the desired level of hardness.
In habitat, soft water environments with low mineral content and low conductivity generally have a low pH (eg; blackwater streams). Likewise, hard water environments with high mineral content and high conductivity generally have high pH. Because of that, somewhere along the way the aquarium hobby decided that the pH was the be-all end-all water parameter to worry about, which isn't really true. In my aquarium, for example, with very low hardness (I use 100% rain water) the pH moves very easily as the water has little buffering ability. I have a large quantity of drift wood in the tank and crushed shell in the substrate. Without the shell the wood would quickly turn the water very acidic, to the point where nitrification would stop and it could be detrimental to my fish. With the shell, there is enough calcium added dissolved into the water to counter the wood and keep the pH stable around mid 7's. Most people would say my South American fish prefer a lower pH, but what they really mean is the fish need soft water with low mineral content. By adjusting the amount of calcium buffering the water I could maintain a pH of 6.5 or 7.8, and it wouldn't make a lick of difference to the fish either way as the hardness/TDS would still be very low.
tl-dr; if you're worried about your pH you should be testing hardness (GH/KH) too. If you don't want the hassle just gradually add wood/IAL/peat and see if the pH comes down naturally. If it does, great, if not you've probably got hard water and need to start catching rain water or using RO if you want to alter it.