You could try Tasker
It can be a little intimidating at first but there are lots of guides online for automating stuff, including this one for sms auto reply.
automation app from playstore is exactly what i use for tracking my kids. i send sms with specific text "where are you" and receive auto reply sms with location (to my specific number only)
found this in changelog to my favorite automation app
Due to new Google Play policy restrictions to prevent apps accessing the SMS inbox:
- Removed monitor inbox ...
It could be possible that your current messaging app is not the default messaging app of the system, thus making messages cannot be removed. Check the default message app in the Settings, and head to the desired messaging app to see if it could be deleted.
You may also consider install the official Android messaging app from Play Store and perform ...
I'm not sure yet whether this works on non-Google phones, but on my Pixel 2 and Nexus 5, the backup feature (under Settings -> System -> Backup -> (Choose profile, if relevant) -> Pixel 2 backup) shows that SMS text messages are included in the Google Drive backup, if you have enabled it. You cannot directly download or view the backup from Google Drive/PC, ...