Her Personality:

Princess Celestia acts as a mentor to Twilight Sparkle. She often does not directly state her goals but rather gives the advice to help her student find the answers she needs. For example, she wrote a letter prompting Twilight to make friends in Friendship is Magic, part 1 when her goal was for Twilight Sparkle to find the Elements of Harmony.

Despite being royalty, she often encourages her subjects to relax through the use of jokes and gentle questions. She also shows great patience with any inappropriate behavior towards her, as seen when Pinkie Pie snatches a cupcake from her at a party in A Bird in the Hoof.

Celestia's mischief with tea cup refills.

Princess Celestia displays a fun-loving side when she chuckles at the bottle of disappearing ink sent to her by Twilight in Griffon the Brush Off. In A Bird in the Hoof, while sipping from a constantly refilled cup of tea, she pretends to sip from her already full cup, causing Mr. and Mrs. Cake to overfill it. She watches with a smile on her face when Pinkie Pie devours one of her cupcakes, while Mrs. Cake gasps and drags Pinkie away. Celestia tells Twilight and her friends in The Best Night Ever, after they ruin the Grand Galloping Gala, that she always found the Gala awful and she was hoping they would liven it up. In Make New Friends but Keep Discord, Celestia invites Discord to the Gala for this same reason, and by the end of the episode, she declares it to be "the most fun Gala in years."

While kindhearted and slow to anger, Celestia's patience does have its limits. When faced against the threat of Discord's return in The Return of Harmony Part 1, Celestia wastes no time in demanding that Discord return the stolen Elements of Harmony. Also, in Lesson Zero, when Spike makes her aware that Twilight inadvertently unleashed mass chaos onto Ponyville in her obsessive attempts to find a friendship report to send to the Princess, Celestia personally intervenes to undo Twilight's out-of-control spell. She sternly orders her student to a private meeting to discuss her actions but remains understanding, and at the insistence of Twilight's friends she agrees not to punish Twilight, instead asking them all to send her friendship reports only when the lessons make themselves apparent to them. In A Canterlot Wedding - Part 1, after Twilight furiously accuses imposter Cadance of being evil, Princess Celestia, along with the others, makes clear her deep disappointment in her student and walks out on Twilight after Shining Armor and the other ponies. But in A Canterlot Wedding - Part 2, while displaying righteous rage to the newly exposed Queen Chrysalis, she eventually commends Twilight for her instincts that told her the imposter Cadance was evil.

Princess Celestia enjoying cake.

In Ponyville Confidential, the Cutie Mark Crusaders manage to get a hold of a photo depicting her eating cake in an unladylike manner for their Foal Free Press gossip column titled "Celestia: Just like us." At the end of MMMystery on the Friendship Express, she admires the cake made by the combined efforts of the bakers and overlooks Pinkie's attempts to gain her attention.

Celestia can also be very forgiving. She does not admonish Fluttershy for taking Philomena without asking in A Bird in the Hoof. As mentioned above, she does not punish Twilight for the chaos she caused in Lesson Zero. In Keep Calm and Flutter On, she firmly believed that Discord could be redeemed, in spite of the trouble he had caused in the past.

She mentions that fall is one of her favorite seasons in Fall Weather Friends while at Ponyville to celebrate the Running of the Leaves.

In Celestial Advice, Celestia reveals that she once shared some of Twilight's anxieties as a teacher, having worried a lot over sending her pupil away to Ponyville and that Twilight wouldn't need her anymore after making her own friends. In A Royal Problem, Celestia is further revealed to have a tense relationship with her sister Luna. Despite her efforts to bring them closer with daily pancake breakfasts, their lack of appreciation for each other's royal duties creates a rift between them, and Celestia demonstrates more impatience and irritation than usual. In School Daze, she shows great trust in Twilight's ability to run the School of Friendship and restore good feelings between Equestria's kingdoms.

In Between Dark and Dawn, Celestia shows a liking for exciting activities while on her vacation with Luna, such as ziplining and diving into the ocean, and shows boredom when Luna takes her to the theatre, or an art museum. During the song Lotta Little Things, she displays a love for stuffed animals, and later in the episode, is revealed to have trouble with maps, and suffer from alektorophobia (a fear of chickens).

Ref: https://youtu.be/IlOL5hgA42w

Try To Sound Exactly Like Her From The Show!