Privacy belongs in every lead form
A quote form that asks for a date of birth before a first call may collect more than you need. The European Commission explains that the General Data Protection Regulation (GDPR) can apply to businesses outside the EU when they offer goods or services to people in the EU. Your form needs a clear purpose and a lawful basis for using personal data.
You can limit the form to details needed for the first reply and explain how you use them in your privacy notice. This reduces the effort needed to ask a question and gives each field a purpose you can explain. Any later marketing use needs its own assessment rather than an assumption that an enquiry permits every use.
Your legal adviser can confirm which consent controls your form and advertising setup need. This is general information, not legal advice.