something like yamaha psr s950 sitar https://www.youtube.com/watch?v=78JTUeC4mQo

Thanks for the question. You can use Aftertouch to bend the pitch three semitones.

Call up the Performance you are working with and select the PART using the [PART SELECT 1-8] buttons
Press [EDIT]
Make sure the lower [COMMON] button is lit
Touch "Mod/Control" > "Control Assign"

What you want to do is ADD a Source/Destination Control Set.
Depending on the selected Part, there maybe several Source/Destination setups already programmed... four are shown per Page. You can advance the Page in the upper right corner.

There can be a maximum of sixteen Control Sets.

Find the first available Destination slot, it will contain a "+" symbol to ADD a new set.
Touch the "+"
A new Destination (parameter) box will appear... touch the default parameter to open the pop-in menu to view all the possible parameter Destinations.
Touch "Element" > "Coarse"
This will allow you to control coarse tuning.

Move the cursor to the box labeled "Source"
Touch it to see your options, select "Aftertouch"

We have mow set Coarse tuning to be controlled by Aftertouch (Key pressure).
Now we can fine tune the application of this control.

The "Standard" CURVE is fine - you want to increase the coarse tuning as you press harder
The "Uni" POLARITY is fine - you want the pitch to return to normal when you release the key
Set the RATIO = +4. With Coarse tuning, a setting of "16" is approximately an octave so a minor third would be about "+4"
Set the PARAM 1 to control the response... the higher the value the later the Coarse tuning takes place - its a feel thing. At "10" you will find the it occurs later in response to key pressure.

Tweak until your comfortable. It takes a few minutes to get used to playing and then applying pressure for pitch control.
Hope that helps.

Thank you very much Bad master for your great help