After Meghan Markle stepped down from her senior royal role in the British royal family and humiliating them in the process, a biographer believes she has even bigger plans.

According to Tom Bower, the Duchess of Sussex's next step is to "conquer the world" just ahead of her 40th birthday on Wednesday, Aug. 4.

In a column for The Sun, the biographer wrote, "Her next steps are to conquer America then the world."

He further said, "Critics carp that Meghan's megalomania has no limits. Her admirers retort that she is purposely fulfilling the American Dream."

Once the former Hollywood actress blows the candles on her 40th birthday cake, Meghan Markle is going to be thrilled about her successes, per Tom, as she is not like other women who are afraid of "toppling over the cliff edge at 40."

Instead, the mom-of-two is still standing and using her voice in the global spotlight - she has become not just a royal or an actress, but also one of the world's superstars where she's convinced her destiny isn't stopping just here but towards "greater fame and fortune."

The biographer also mentioned how in the past 18 months, she ignored Queen Elizabeth II, Meghan Markle, and her husband, Prince Harry. They purchased a $14.7 million mansion in California, thanks to their multimillion-dollar contracts from Netflix, Spotify and their four-book publishing deal.

At the age of 40 years old, Tom believes the Duchess feels like she is at the height of her powers as she has also become the navigator of her narrative and her husband's fate.

And at this milestone age, Meghan should "congratulate herself on defying all the odds."

READ ALSO: This Is How Queen Elizabeth II Will Respond To Prince Harry's Book Once It's Out

Meghan Markle' 40th Birthday Party Details

The news comes after reports that the former briefcase girl of "Deal or No Deal" is hiring Oprah Winfrey's party planner for her 40th birthday celebration.

The Duchess of Sussex will reportedly host 65 people and will not break COVID-19 restrictions in California.

She also has reportedly tasked Colin Cowie with planning her 40th birthday, known to be the best person for luxurious parties for A-list stars including Kim Kardashian, Jennifer Aniston and Tom Cruise.

Meanwhile, Prince Harry has already ordered a cake from a local baker, Posies and Sugar, according to The Mirror, but the celebration will be a low-key party.

An insider revealed that the guests would also enjoy grazing tables sourced locally.

READ MORE: Queen Elizabeth Secret At-Risk of Being Revealed in Prince Harry's Book

Tags: Meghan Markle meghan markle birthday Prince Harry meghan markle mansion