In order to change that setting you will need to unlocked developer option by go to setting and scroll down and click on "About Phone" then click "Software Information" and click Build number 5 or 6 times to unlock the developer mode.
Then back to setting and scroll down and click on "Developer option" then scroll down until you see "Window animation scale"," Transition animation scale", and "Animator duration scale", make sure you change these setting at 0.5x or no animation. Thus method will help you open the app and close the app faster. DO NOT CHANGE OTHER SETTING UNLESS YOU KNOW WHAT YOU DOING, I SUGGEST LEAVE OTHER SETTING AS THE WAY IT IS.
the other way to make your phone faster is by doing wipe catch partitions. this will definitely make your phone faster but I suggest you to study on youtube first then take your action when you feel comfortable