I guess you deleted your last question and are asking again, because I know I answered this before. So I'm just going to repeat the same information because that is the answer to the issue. It's up to you to run with it.
This is the first thing you ask:
"Will the pH go down after a few days?" Based on what though? On it's own? Not likely, as what you are seeing is the pH out of tap.
"Are there any Natural Ways to lower pH without using chemicals like "pH down" or "Ph Decrease"?" Repeat of what I told you earlier. Peat Moss, Driftwood or Bogwood are natural ways to deal with this, but what you are not realizing here though, is what drives or makes the pH what it is, is the GH and KH. That is why companies make so much money keeping people focused in on the pH when the pH itself is actually a very minor thing.
What you want is the wood or moss to do is eat away at the hardness in the water. When that hardness comes down, the pH in turn will come down. The woods emit tannins into the water which counter act with the cations in your water. I am not exactly sure how the Peat moss does it, but I do know it softens up the water. The problem with the woods though is that after a few months, the tannins will stop being emitted as it's all used up.
What I suggested before, and this is probably your best way to handle this, is to make use of RO (Reverse Osmosis) water. The RO water will be devoid of the cations and other minerals and work to lower your GH and KH which means your pH eventually goes down as well. I would use half tap half RO because it's a bad thing to leave your water totally devoid of the cations you need.
I hope I don't have to repeat this again.