Should I back up my phone to iTunes in addition to the cloud before getting a new phone

About backups for iPhone, iPad, and iPod touch - general comparison of using iTunes vs. iCloud - https://support.apple.com/HT204136

Do you have to backup to iTunes before to get the phone, no, it’s not necessary, but I think that would be an excellent idea simply because having multiple backups is always a good thing. While the odds are slim, you never know when a backup could get corrupted.