Unrest in France is already tarnishing the sheen of King Charles III’s first overseas trip as the British monarch, with striking workers literally refusing to roll out a red carpet amid pension reform protests and calls for the visit to be canceled altogether.

Charles is scheduled to undertake the trip beginning Sunday on behalf of Prime Minister Sunak’s government, which hoped a short royal tour would underscore efforts to rebuild Anglo-French ties that were frayed by Brexit.

Yet anger over President Macron’s resolve to increase the retirement age to 64 from 62 are clouding what was meant to be a show of bonhomie and friendship. Instead, Charles’s visit is being widely perceived, at least in France, as an unnecessary display of hereditary privilege.

“It’s very bad timing. Normally the French would welcome a British king. But in this moment, people protesting are on high alert for any sign of privilege and wealth,” a Paris-based writer, Stephen Clarke, the author of “Elizabeth II, Queen of Laughs,” said.

With piles of uncollected garbage lining the French capital’s once-pristine boulevards, observers say the optics could not be worse — for both Charles and Mr. Macron.

French labor union CGT announced this week that its members at the institution in charge of providing red carpets, flags and furniture for public buildings, Mobilier National, would snub a Sunday reception for the king upon his arrival at Paris. “We ask our administration to inform the services concerned that we will not provide furnishings, red carpets or flags,” a CGT statement read.

The Elysee Palace, the French president’s official residence, said that non-striking workers would set up the necessary accouterments for the trip instead.

Months in the making, Charles’s glamorous itinerary with the queen consort for the March 26-29 trip includes a visit to the Musee d’Orsay, a wreath-laying ceremony at the Arc de Triomphe, and a lavish dinner at the former French royal residence, the palace of Versailles.

“They’re planning on going to Versailles. It does not look good. This seems very 1789,” Mr. Clarke said. The opulent Versailles, once the dazzling center of royal Europe and a focal point of the French Revolution, is an enduring symbol of social inequalities and excess.

Mr. Macron is facing a public backlash for pushing through a bill raising the retirement age sans a parliamentary vote. Some opponents accuse the president of being out of touch and acting like — mon dieu — a king.  

“Unbelievable. We are going to have Emmanuel Macron, the Republican monarch, welcoming King Charles III in Versailles … while the people in the street are demonstrating,” a lawmaker with France’s Green Party, Sandrine Rousseau, told French channel BFM TV. “Of course” the king should cancel his visit, she added.

The French have maintained a love-hate relationship with kings ever since they guillotined King Louis XVI in 1793. Queens have typically fared better since then. Queen Elizabeth II, Charles’s mother, was a hugely popular figure in France, the European country she visited the most before her death last year. Elizabeth, who spoke fluent French, made five state visits to France, in 1957, 1972, 1992, 2004, and 2014, as well as unofficial and private visits. 

“The problem with Charles is that he is not the queen. She was very loved here,” a Paris resident, Geraldine Duberret, 62, said. “Charles does not have such a good reputation here. He seems a bit spoiled.”

The celebrity press in France recently focused on unconfirmed rumors that the king would travel with excessive numbers of servants, comparing him to his late mother, who famously insisted that her staff turn off light bulbs in Buckingham Palace to save energy.

“This visit was a chance for Charles to relaunch himself in the eyes of the French,” Mr. Clarke said. “It could have been like a blank canvas, but he will likely not be able to have the impact he would have wished.”

Charles does command some respect in France for his environmental activism. The king and the queen consort plan to tour areas of France’s Bordeaux region, which last year were ravaged by wildfires widely blamed on global warming.

Regional officials are effusive about receiving the royals, a stark contrast to the reception Charles and Camilla could expect in Paris. “It’s very touching that Charles plans to come to Bordeaux. We have a very strong relationship — and historic — with the U.K. The region stayed English for three centuries. It’s in our DNA,” Cecile Ha of the Bordeaux Wine Council said.

In the French capital, though, the prevailing mood is one of social turmoil. There have been clashes between protesters and riot police at the Place de la Concorde, in the center of Paris, where in 1793 Louis XVI was beheaded by guillotine. At that time, the iconic square  was called the Place de la Révolution.

By the end of the day on Thursday, fresh demonstrations over the reform bill were drawing record numbers, with Le Figaro reporting that 119,000 people had “mobilized” at Paris. The CGT union said the figure was several times higher. Many major roads were blocked, sporadic clashes were breaking out, and the newspaper described the atmosphere in the capital as “very tense.”