Why does it need smaller provinces? For voting reasons or other reasons?
You can separate the political and the voting districts, at least when you are voting on higher levels.
Also there is a question if you want to expand the current system (ie more provinces), or if you want to add a new layer into the chain (ie sub-provinces). Both can be good depending on what you want to achieve.
Britain is currently introducing new layers. They have new district mayors for new major regions.
But Britain is quite strange in how their system works, mostly because they has not been a real revolution for 800 years.
What has happened over the past few decades is that all the provinces have spent most of the development budget in the area close to the provincial capitals. The reason is a mix of governments operating on limited budgets prioritizing certain areas to get maximum short term gdp growth, and ethnic racism/corruption/etc.
Now, people in the undeveloped areas correctly feel like they are not represented by their governments. Creating more provinces means more spread out development. It also prevents the largest province from bullying the federal government into complying to its whims.
There are already 1.5 administrative layers below provinces (thanks to Britain I might add), but they don't function well at all. But that discussion cannot fit into a HN comment.