Whether or not you will get wet when paddling out on a lifetime sit on top kayak depends on the model you are using. The 10' kayaks you may get a few drops, but only from the paddles. It is literally only a few drops. The youth kayak has the potential to get the most wet. The youth lifetime kayak and other kayaks have drain holes that go right through the kayak to the water to drain water that gets on the top of the kayak. You can purchase foam plugs to keep little splashes of water from finding their way up through the bottom and onto the top of the kayak. That's also the case with the 8' and 10' kayaks; they have holes, but the foam plugs are included. So, if you don't want to get wet make sure you've plugged the holes.
Also, river water or white capped waves are also more risky if you want to keep dry in cold water. If you want to go kayaking and keep totally dry choose a calm weathered day and a calm watered lake and you should be fine with the exception of a few drops.