Hi,
To my understanding you want to use the external clock output (XCLKOUT) feature of GPIO16 on the F280015x microcontroller within Simulink.
I don’t see a direct way to use this feature on SIMULINK.
But the support for this board is added in MATLAB R2023b. You can refer to the release notes for more information on the support added in the C2000 Microcontrollers Blockset in MATLAB R2023b.
Hope it helps!
Regards,
Soumnath