I currently play on a Cannonball Sceptyr Tenor sax, an Otto Link STM 7 and Vardoren Java Green box reeds. The sound is not what I am looking for as it is too bright and not that classy, warm, jazzy sound. What are some good ways to warm/darken up the sound?
In general any metal mouthpiece is going to be more strident than a rubber one. All the same, I would hesitate to give specific advice without observing you "live." It may well be that you are playing with an excessively tight embouchure and/or reeds stiffer than you can easily control, for example.
If you can get some sax teacher to work w/ you, that will help.
The other easy thing to do is go to a music store and play a few other brands/models of tenors with your existing mouthpiece and reed, and see if they come closer to the sound you are attempting.
Practice lots of long tones and slurs. Almost all successful jazz sax players practically only play long tones during practice time to work on their tone. I also would suggest playing with different shapings of your embouchure to see if you can find the tone you are looking for. Don't think too much about the instrument you are playing with.
The best musician can make a $10 instrument sound like a work of art.
A practice that I do on wind instruments is closing my eyes and visualizing a deep red while I play, my elementary school teacher had our band do this exercise to help the younger less experienced players focus on their tone and realize if they were out of tune, but I find that it helps in creating a rich tone, and have requested that each ensemble, even vocal, that I preform in to do this exercise, and I have found great success in doing so.
Moving up a size in reeds will give you a less strident sound. If your reed is too soft, the sound you'll get is going to be brighter. Try switching to a french filed reed, such as Java Reds, since those will also play a little warmer because of their cut.
A rubber mouthpiece, like the Morgan Excaliber or Jody Jazz, will also give you a darker, slightly more breathy tone, especially if you go for a bigger tip opening. The metal mouthpieces tend to be much brighter.
There are many different things that could be going on with embouchure, air flow and support, but without seeing/hearing you play, it's difficult to diagnose. I recommend sitting down with someone in person and having them help you solve some of those issues.
Its is impossible because is it not a synth. you can only have "1" sound in THIS saxophone. Exactly like a piano or a college flûte.