There are a lot of options in real band that can help improve a vocal tracks, but if the vocal is really bad, try re recording just the vocal track to improve the performance. When I record my songs I usually record three vocal tracks. I use the best of three, and use the other two to cut and paste to fix any parts I'm not happy with.

First get the vocal track to a volume level you can work with. Select the whole track, and using the audio effects apply a gain change. I like to get the waveform about 2/3 of the track height so there is room for expansion, but it is audible.

Apply some compression using the audio effects. A ratio around 1:1.7 and rapid attack is usually a good starting point.

Once you get the volume levels suitable you can use reverb and equalizers to help improve the sound. That should be done in the mixer AUX, rather than the individual track, so the original track remains unchanged, and you can try a lot of different mixer settings.

Again don't waste a lot of time with a really bad track. You can spend hours trying to tweek it and still be unhappy. I learned the hard way it is much easier to re record the vocals.

Good luck
Brian