If you know your team's velocity, this methodology has worked well for me in the past:
- ask enough questions about the scope of work to do a prototype
- build a prototype to identify constraints / complexity
- ask followup questions
- break the body of work down into a list of tickets (spike/discovery tickets included)
- use the PERT formula to estimate the total number of story points for the body of work
- take the total estimated points and divide by your team velocity for a duration of time (e.g. 100 total points / 40 points per 2 weeks = 2.5 weeks)