I hate to be a pessimist about aliens, but the only data we have to extrapolate from is our own planet.

Here on Earth, any time a more advanced civilization has come into contact with a less advanced one, things went poorly for the less advanced. Even if it's a relatively "civilized" culture that frowns on things like genocide and slavery the advanced culture tends to overwhelm, stunt growth, etc. for the less advanced.

And same with interspecies interactions. If a more successful species shows up in the same niche, the locals suffer, every time.

Our own culture does seem to be sliding more and more toward wanting to shield low-tech cultures from being forcefully modernized, to the point that we now try not to contact indigenous tribes at all if we find them. I suppose our best hope is that most alien cultures go the same direction over time.