Yes, ducking is available in Vegas Pro.  Hitting keyboard "V" will activate the volume line on your audio tracks, though the audio tracks will need to be expanded beyond minimum track height in order to show the blue volume line.

Double clicking on a chosen point on the blue volume line creates a key point (for want of a better term),  Right clicking on the key point gives a lot options including the volume desired for that point.  Particularly good is the 'set to' option which allows you to code a specific +/- dB value.  Typically of course, there would be 4 key points for ducking: the first to maintain the preceding volume (e.g. 0 dB), the second being the + or - dB value that you want the volume faded up or down to, the third usually repeating that value at the end of the ducking length, and the fourth returning the volume back to the original volume.

I do not believe that Vegas Pro provides an auto ducking option, though Vegasaur provides an auto ducking option that operates track-by-track, but not across all tracks in the one run.  I did try it once but it really didn't suit my needs at the time.

Vegas Pro has automated audio mixing which may help..  Not being familiar with auto mixing, I hope that others may be able to advise whether or not the automated functions could assist you.

Cheers