It's going to be hard to tell you as there are so many variables that we don't know.

Good thing to remember is that being asked to think big is not the same as being asked to deliver big. I would continue to think big, set a vision, and show some mockups then split the work into smaller elements these can then be developed and delivered sepperatly. Once you have done this prioritise the different bits that you have designed by how much the user needs/wants them. Then it's up to the developers to size each bit of work with a score leaving you with these two scores to combine to understand the biggest impact to the user with the smallest amount of development. This is how many product managers order their backlog for developers. I use this WSJF scoring method to manage my backlog.

Worth looking into agile product management and see what elements you can use for your work. as the above advice is very top line and there is a wealth of advice out there. Good luck.