This is the hardest part about trunk based development - changing your way of thinking. Everything needs to be decomposed into much smaller changes, and you need to think about the impact of each of them being deployed into production (since that will happen). New features should exist behind some kind of feature gating or dial-up capability, or a new API version with restricted access, etc.

That seems painful but it's less painful than merge hell or deploying a change with a massive delta to production and needing to roll it back and unpick what went wrong.