Yes, washing clothes at 20°C / 68°F or 30°C / 86°F can be enough.
Using low temperatures in washing machine is suitable for clothes that are not "too dirty".
30°C / 86°F is usually enough for everyday laundry.
Washing clothes at low temperatures generally extends their lifespan.
To wash clothes at 20°C / 68°F or 30°C / 86°F, you have to use a washing powder or washing liquid, that is suitable for low temperatures.