First step would be to install the universal Android debloater. It can remove unwanted preinstalled apps over ADB. If your phone is supported by TWRP it might be possible to replace Google Play Services with microG, but I’m not entirely sure if that works without root. Didn’t manage it on my phone but that might be sure to the fact it isn’t supported by TWRP and I had to hack a custom version of it which kept getting uninstalled by the stock ROM on every reboot.