Can I bring large luggage in a private taxi in Sri Lanka?

Yes, you can bring large luggage in a Sri Lankan private taxi, but you have to tell them the luggage size and how many pieces you have when you book, so they can assign a suitable vehicle.

In most cases, a regular sedan will fit two large suitcases plus two carry-ons, and it will still be reasonably comfortable. However, if you are travelling with surfboards, a lot of camera equipment, or you have a bigger group, you should request a minivan like a Toyota KDH, because it can hold the extra cargo without squeezing everyone inside.