battery saving mode on apple watch 6 ?

Yes, it is called power reserve.

Looking at your watch face, swipe up to access the control center. Tap battery (it will display your battery percentage), and then slide the power reserve icon to the right to turn it on.

If you want to turn off the always-on display, on your watch go to settings > display and brightness > always on > and then turn off always on.

Yes;

Power reserve mode;

To enable Power reserve mode,tap on settings/battery and scroll down to the bottom and slide the switch.

This mode turns off all Watch functions except the Clock, allowing you to consume as little battery as possible and still use the timekeeping functions of the Watch.

The Apple Watch also automatically enters Power Reserve mode if the percentage of battery charge remaining drops below 10 percent.

And;

To enable Workout Power Saving Mode, open the Apple Watch app on iPhone, tap My Watch, and then tap on Workout > Power Saving Mode and turn the switch on.This turns off the heart rate monitor during walking and running workouts.