It must descend, but when you get a pilots' license you learn to keep up a minimum speed recommended for best glide distance. That means adjusting its descent angle until it is flying at that speed. Its weight is not relevant, if heavily loaded it will just descend faster.
You can fly that all the way to the ground, and carry out a quite normal landing IF there is somewhere suitable to land. So while you are gliding, you are looking for what appears to be the best landing spot. It could, for example, be 2,000 feet below where you are at that time. In which case, you begin to circle while losing altitude, until you judge you can make an approach to land. There are other techniques like sideslipping than can be used to lose height fast if required.
Increasingly now, you hear of light aircraft landing on highways if vacant, or among traffic on highways IF traffic is moving in the same direction and spaced enough, such that the first car that sees you coming down ahead of it has the time to brake and allow you to land ahead of them on the road. I have not yet heard of any motorist being injured by being hit by a plane landing with problems, have you?