I can help you my friend you and anyone who have drain and bad battery life. All this apps who i will write, you can find this apps from the playstore. Expect Youtube Vanced and Adhell2. For more help you can pm me anytime.
1) Add Nova Launcer : Best and fastest launcer ever, reduce phone and animations lag.
https://play.google.com/store/apps/details?id=com.teslacoilsw.launcher&hl=de_AT
2) Install Naptime with adb : Best Doze app for a better phone sleep. Check agressive doze.
https://play.google.com/store/apps/details?id=com.franco.doze
3) Remove apps from your phone like malwarebytes and antivures and ram managers. You dont need this craps. You have android 8 and soon 9 not android 3 and 4. Just unistall this noob apps.
4) Use Youtube Vanced : Best youtube with dark mode,background playback,and big support, low wakelocks, and many more.
https://youtubevanced.com/non-root
5) Use opera browser : Have dark mode and 0 bad wakelocks like chrome and some other crap browsers.
https://play.google.com/store/apps/details?id=com.opera.browser
6) Remove ussles apps who dont use from your phone.
7) Use Appops app with adb : Helps to close the background apps who run without need it. And help to close some critical permissions like apps wake up, no boot, no stay awake at background.
https://play.google.com/store/apps/details?id=rikka.appops
7) Use adhell2. This app is the best app for the non root samsung phones. He can block the wakelocks,freeze apps,and improves the phones battery life very much. But he need to read the tutorial how to install. Is very easy.
8) Always use dark themes. Oled screens loves dark themes. White thems gives a battery drain and burn in sometimes. I dont recommend white themes for oled screens. Try to make the apps background dark too. With 3rd party themer apps.
9) Use screen resolution WQHD+ and lower the screen DPI and lower nova launcer animations too.
10) If you make all of my steps correct. Add the betterbattery stats app into the phone and follow the xda site tutorial how to find the bad wakelocks and the fix the drain. And you will see a very clean phone with low bad wakelocks and big battery life for sure.
https://forum.xda-developers.com/showthread.php?t=1179809
Adhell2 tutorial site.
https://forum.xda-developers.com/galaxy-s8/themes/adhell-2-rootless-ad-blocking-t3663559
An easy video tutorial how to install adhell2.
https://vimeo.com/251025718
Extra tip: facebook,instagram,snapchat,skype Is the 4 badest apps ever. If you dont use this apps. I can say you how to remove this apps without root permissions. And will helps a lot the battery life.
Read this is all true.
https://www.makeuseof.com/tag/do-not-install-10-popular-android-apps/
If you make all this steps im pretty sure your phone will change soooo much without root. And you will be able to beat the rooted phone easy without root. This apps will helps you to learn better about the android and how to have big battery life anytime.