HOW WOULD WE DO IT?
If we found another planet with evidence of life, particularly intelligent life, and we managed to fund the exploration in a sustained way to study that life, we would likely send robotic probes and/or use telepresence to study that world. It’s cheaper and less dangerous. We would likely take precautions not to infect that world with Earth bacteria and viruses or other lifeforms or with lifeforms from the space between our worlds lest we bring dangerous lifeforms to them. We would likely determine whether this other advanced civilization poses any kind of threat to our world before we decided upon establishing any kind of formal contact or making entreaties to formal relations. It is logical to assume that this is the approach an alien civilization is taking toward the people of Earth.