@ekjk Yes, it's possible. One way is to route the same input event on D6 to anonther timer, set to start counting upon receiving the event. Upon timing the delay (match compare), this timer sends out an event to yet another timer set to oneshot mode that outputs a single pulse of a specified length.
I've written something similar on the Arduino forum here: https://forum.arduino.cc/t/pwm-generation-for-a-very-low-duty-cycle-and-phase-shifting-capabiliy-on-samd21/644736/7.