generally this is a no (the exception kind of being pixel/nexus devices) running non official roms and mods requires an unlocked bootloader which is something o

generally this is a no (the exception kind of being pixel/nexus devices) running non official roms and mods requires an unlocked bootloader which is something only the manufacturer can provide, some devices like for example huaweis mate 20 pro have no option for unlock/root at all (unless you already got your bootloader unlock code before huawei closed the service) that doesnt mean yours is impossible though, let me know the model and i may be able to help