The requirements should be seperated into "minimum in-out workflow or MVP", then slowly add features which are a balance between high priority and easy to imple

The requirements should be seperated into "minimum in-out workflow or MVP", then slowly add features which are a balance between high priority and easy to implement (With a clear way of saying "No" to impracticle requirements). This is generally the "Agile" approach. However at some point its always better to have a complete architechture diagram and work from there. Of course choosing between a monolithic approach or modular approach (or microservices) is also very important at the beginning of the project.