Is it permissible to alternate relying on one leg or standing on both legs during Tarawih prayer to alleviate fatigue?

This act is called "alternating," and it means that the worshiper leans on one foot at times and on the other foot at other times. This is permissible in prayer, especially if the standing is prolonged. There is no harm in it as long as one foot is not placed in front of the other. It is disliked if done without an excuse.