There are serveral ways to harden your stock android. First uninstall bloatware using this video: https://www.youtube.com/watch?v=YYMY5dOPV1g
Then harden your settings and make sure you follow the new oil and privacyguides apps and settings to follow. Techlore may have some guides aswell.
Conclusion:
For more better privacy, Just use GrapheneOS!