Summary

• Leia Organa has been using the Force long before her Jedi training, but her use and strength became more tangible after training from Luke.
• Leia's use of the Force was not always noticeable to Palpatine and Vader, as it was more subtle in her rhetoric and they were not present at Senate meetings.
• Leia has had encounters with the Force throughout Star Wars, both good and bad, including saving her son and being tempted by the dark side.

Leia Organa used her connection to the Force in Star Wars long before she trained to become a Jedi. While Leia wielded the Force in order to sense Luke throughout the later part of the original trilogy, she wasn't seen using the Force in a grander and more tangible way until she saved herself from the vacuum of space in Star Wars: The Last Jedi. That difference in use and strength no doubt resulted from the training Leia received from Luke, even though the Force has always been flowing through her just as it had her brother.

Leia has quite a few other encounters with the Force, both the good and the bad, throughout Star Wars media. She was able to save her son, Ben Solo, from his Kylo Ren dark side in Star Wars: The Rise of Skywalker just by reaching out to him. On the other hand, the hatred she felt from encountering the remnants of Darth Vader's funeral pyre in Beth Revis' The Princess and the Scoundrel brought her close in touch with the dark side itself. In reality, Leia had actually been using the Force all along, and she had used it in her fight against the Empire.

Leia Used The Force To Challenge The Empire In The Most Powerful Way

The story "From a Certain Point of View" by Alex Jennings, featured in From a Certain Point of View: Return of the Jedi, reveals that Obi-Wan Kenobi had sensed her using the same power of the Force her father had once used for sparring in her rhetoric. Obi-Wan's Force ghost spends a brief part of the narrative ing Leia, both recalling the little girl he met as well as the progress she made in her political sphere. The contrast of her gentleness with her fiery retorts caused Obi-Wan to realize that her style of speaking used the Force just how Anakin wielded it in his fighting.

Even as years ed, Obi-Wan thought of Leia as that same little girl he'd spoken to on the landing pad, but he had followed her progress carefully. Her rhetorical style was sometimes gentle, and sometimes fiery, each swell and retreat applied deftly - sometimes in the same sentence. At first, he'd wondered where he had heard it before - until he realized he hadn't heard it at all. He'd felt it in his sparring sessions with Anakin, and in his duels with Vader after his former pupil had fallen to the dark side. Leia's voice and bearing were a lightsaber, and she wielded it with impeccable mastery.

Why Didn't Palpatine & Vader Ever Notice Leia Using The Force?

While Leia's use of the Force had been powerful, it likely hadn't been as substantial or obvious as it had when fighting a physical battle. It's also likely that Palpatine and Vader simply hadn't attended Senate meetings enough to notice the kind of energy Leia put behind her words. They had no reason to believe that Leia could wield the Force in the first place, and if Vader hadn't noticed it during their exchange at the beginning of A New Hope, then he surely wouldn't have identified it within the Senate chambers.

It's interesting to think how Leia could have used the Force in unexpected ways throughout Star Wars. Her strength with the Force is a part of her character that's only just started to be explored in more depth, something that can be credited to her acting as Rey's final master in The Rise of Skywalker. With the direct comparison by Obi-Wan to Anakin, there's no doubt Leia was strong in wielding the Force in ways both known and unknown.

Source: From a Certain Point of View: Return of the Jedi