Here is a good theme for you, the theme is not mine .... But the developer has no account here on xda, any updates I post here.
Just flash the file on magisk and restart
PUI6 For OP8T OOS11 Beta5 Theme
6.0.1 Update content:
•Adapted to beta 5
•Beautify as Magisk module, which will take effect after flashing in and restarting
•This version is a beautification of OOS 11, and the limited system is the OOS11 Please do not flash the other versions
Credits : @FifthSnow Telegram!