Swiatek, warming up for the defence of her French Open title, claimed a 6-3, 6-2 win over 29th seed Pera for a sixth consecutive victory on clay this season.
"I wouldn't say it was easy. Every match is tricky here," Swiatek said after her 75-minute outing.
"I'm happy that I'm getting my rhythm. Playing against a lefty is never easy... but I'm pretty happy that I was disciplined and focused."
Swiatek next faces 16th seed Ekaterina Alexandrova after she beat Chinese 22nd seed Zheng Qinwen 5-7, 6-4, 6-2.
Also progressing to the fourth round on Sunday was world number three Jessica Pegula who clinched a gruelling 6-4, 7-6 (7/2) victory over Marie Bouzkova of the Czech Republic.
Pegula made the final in Madrid in 2022 where she lost to Ons Jabeur. She will now tackle Italy's Martina Trevisan on Monday for a quarter-final spot.
Defending men's champion and world number two Carlos Alcaraz continued his bid to win a 10th tour title before his 20th birthday by beating Grigor Dimitrov of Bulgaria. The match finished 6-2, 7-5.
Two-time champion Alexander Zverev of Germany needed just 56 minutes to dispose of France's Hugo Grenier 6-1, 6-0 on the back of six breaks of serve and 26 winners.
He will face Alcaraz for a quarter-final place next.
"Both are great players," said Zverev. "It's going to be difficult no matter who it is against. Of course with Carlos that would be a matchup people would look forward to.
"We played in the final here last year, played a massive match at Roland Garros before I got injured."
Zverev holds a 3-1 record against Alcaraz with their last meeting coming in that quarter-final clash at the 2022 French Open.
World number seven Holger Rune, who left his teenage years behind on Saturday, faces Spaniard Alejandro Davidovich Fokina in the last match on Sunday.
Rune, making his tournament debut this year, had to save a match point in the last round against Alexander Bublik.