The claim is true because Paramount's own announcement and Variety's reporting state that the Season 3 premiere reached 7.1 million viewers during its first seven days of streaming.
‘Lioness’ Season 3 attracted 7.1 million viewers within its first seven days.

‘Lioness’ Season 3 Opens With 7.1 Million Viewers in Seven Days, Up From Season 2 (EXCLUSIVE)
Source: variety.com
Key Evidence
Paramount's published announcement directly reports 7.1 million viewers in the premiere's first seven days of streaming.
Variety's report, published two days before the current date, independently gives the same seven-day figure.
The Express Tribune is the only supplied source that changes the timeframe to three days, but it is outweighed by the direct Paramount statement and consistent Variety coverage.
What the Evidence Shows
The available evidence supports the claim as stated. Paramount reported that the August 2 Season 3 premiere drew 7.1 million viewers in its first seven days, based on the company's internal viewing data. Variety independently reported the same seven-day figure, and its Australian edition repeated the result.
Several secondary outlets also reproduced the 7.1 million figure. Mxdwn Television, ScreenRant, and ComicBasics attributed the result to Variety or Paramount's internal data. IMDb appears to host or reproduce Variety's report rather than provide an independent measurement.
One source, The Express Tribune, described the 7.1 million viewers as being reached in the first three days rather than seven days. That conflicts with the more direct Paramount announcement and the two Variety reports. Because the primary source and the principal trade publication specify seven days, the three-day wording appears to be a secondary-reporting error or a misstatement. The Mirror article concerns the episode release schedule and does not provide relevant viewership evidence.