Less Extreme Power Saver Mode?

[AC Question]

I have had an HTC one M9 running android 6.0 for about 7 months, and I have noticed that my phone's battery dies really quickly. This is my first android, but I have heard about and seen other android phones with a power saving mode where it just reduces CPU power and screen brightness. My phone seems to only have "Extreme Power Saving Mode" which essentially just turns my phone into a potato or an early 2000's flip phone. Is there some way that I can save some power (maybe not extreme amounts), but still use my smartphone as a smartphone?