I use regex code but i want not type more than 11 digits

I want to do regex (., ‘[0-9] 11} $’) but not type more than 11 digits.

Welcome to the community, @mdnurnabi! Try the following regex code:

regex(., '^[0-9]{11}$')

Note: You will have to make the question type as text and appearance as numbers. For more regex code, please visit our support article Restricting Text Responses With Regular Expressions.