They were commanded to have children so that the world would be filled. The AV use of the word replenish needs noting as a word that has changed its meaning. It means fill up rather than, as today, fill again. Adam was the firstborn of God’s creation; their task was to fill the earth with children. They were to bring it into subjection and have dominionover it. God gives a broad sweep of what man is to subdue covering all creation, except for man himself. Unfortunately man has sought to subdue his fellow man, bringing much misery and death into the world. Things will be rectified under the wise rule of Christ. Dominion was not t intended to be exploitive, but beneficial. Man was to use his skills and wisdom for the benefit of nature.
The chapter ends with the detailing of food that God had provided for all creation in abundance and vegetarian in nature.
Having completed what we could term the active part of creation God declared that it was very good. And so this special day, described as a Daythe sixth came to its close and the section ends with these words:
Thus the heavens and the earth were finished, and all the host of them. 2:1
The work was complete and yet it wasn’t quite finished.