Is there a option where user can choose as many multifactor process he wants while logging into the OKTA org (Atleast 2 factors he have to choose,it is mandatory, other factors he may or may not choose)
This will depend on the number of MFA types that have been configured aginst the Okta tenant and based on the registration policy that you define for the groups of users. If in the admin interface you select "Security", "Multifactor", "Factor Enrollment" policy tab. You can then define policies for different user types/groups, and then associate different rules for MFA option type(s). Below is an example for Admin users, what MFA types, and when the user would be expected to register for them.
I have done this Kevin. I want to know if there is a option where user can choose which type of multifactor he/she wants out of 5 or 6 factors but he/she have to choose atleast 2 factors for going forward
Yes, you would use the options of Required or Optional. So as I have on my example policy, admins must enrole for Okta Verify and the Yubikey token, but all others are optional, and Security Question is disabled.