Yes, but practically with todays technology there is no feasible way of getting to a speed where time dilation matters over that distance, we run out of fuel so we need some external power source like a laser or solar wind that have other issues, iirc one only gets to 2x time dilation at 0.9 c. That’s a lot of acceleration.
We need to think about where we want the knowledge and what knows it. We could use humanoid AIs. We could hatch humans "just in time". Run them in a sim to 18 then release them on their mission. Ethics would need to accept this. Maybe we would be happy slowly expanding across the universe and an decendant talking to 'the aliens'.
I am not totally serious. But you wanna meet aliens? Gotta do something a bit radical.
If you haven't, you should read Accelerando, it's a collection of short stories IIRC that were put into a novel by the author. I didn't want to start with that, but that is in there. :)
If I may suggest another read: Perfect Imperfection by Polish author Jacek Dukaj. It's definitely weirder, than Accelerando, as the book drops you straight into the last parts of evolution curve, but definitely worth reading if you have liked Accelerando.
The story is super weird, but what I found out is that piecing together a picture of a far-future society from this story was very exciting.
