If you want to apply conditional validation on 'Middle Name' or 'Last name', then you need to add 'First Name' input as 'Bharat'
{{userForm.controls?.firstName?.errors?.maxLength.message}}
To apply the validation of lowerCase on 'Last Name' field, write 'Bharat' in 'First Name' textbox because it is conditional expression. and maximum length is 16
Conditional Expression with type 'string'
{{userForm.controls?.lastName?.errors?.maxLength.message}}