Hey there, and welcome to Apple Support Communities sathya1,
We can certainly understand your concern and are here to help as much as we can.
Just to clarify, when you say "OTP" are you referring to one-time password? If so, check out these steps for more information on how to use one-time-passwords and see if everything matches up on your side.
" Automatically fill in SMS passcodes on iPhone
When you sign in to some websites and apps, a one-time SMS passcode is sent to your iPhone. As a security measure, you’re required to enter the code into the website or app. iPhone can detect the passcode in Messages and display it above the keyboard.
To use the passcode, tap it.
Note: With Continuity, all the SMS and MMS messages you send and receive on iPhone can also appear on your other iPhone, iPad, and iPod touch devices and your Mac. See the Apple Support article Use Continuity to connect your Mac, iPhone, iPad, iPod touch, and Apple Watch. "
For additional information, check out this link: Automatically fill in SMS passcodes on iPhone - Apple Support
Kindest regards!