Well,
If it still crashes after the Keyboard Dictionary Reset, you should restore your iOS device then.
Before you do that, make sure to back up your iPhone to iCloud:
→ How to back up your iPhone, iPad, and iPod touch - Apple Support
When you do that, Restore the software using iTunes:
→ Restore your iPhone, iPad, or iPod to factory settings - Apple Support
Hopefully, the new software will fix the issue.
Cheers !