Working on an enterprise product, how often do PMs get a chance to make a significant impact? (As opposed to work on small/specific features)

 The impact that a product manager has depends much more on the type of product team and its role in the company than on the product's market (B2B, B2C, SMB, mid-market, enterprise, &c).

Even for a miniscule aspect of a product, the PM has an opportunity for tremendous impact when they have responsibility for the full lifecycle and access to the end customer/user. They will be able to generate real insights, solve real problems, and deliver real value.

The best product management teams deliberately organize themselves to ensure maximum responsibility and access, even as individual PM scopes may narrow as the team grows.

No one answer suits all situations! 

Often the impact of a feature is not based on the size/complexity of the feature, but rather the 'value' it can deliver for our customers and most importantly - if it sets us up for launching more impactful features in the long term where it can become an enabler.

As an example, when I was looking at reducing the cost of text messaging for our CPaaS platform- we were working with multiple vendors and each had certain minimum volume commitments and different price points per text message. I proactively took up an 'academic' style study to see if there was scope for reducing cost. I called my little module a 'Least cost router', that pushes the text message out via the cheapest path until the minimum commitments were met but in real-time. A seemingly boring feature that nobody 'wanted' or thought would be necessary, but once we ran a small pilot simulation we saw that we could easily save 30% on the costs. Implementing it meant we boost our profit margin directly. When our volumes and our global reach grew, this had a wider impact and played a pivotal role in maintaining profits.

Doing our best work, and delivering value will always lead to a lasting growth story that can be truly ours :)