Early success and setback (2018–2022)
Khan's acting debut came in 2018 with Abhishek Kapoor's romantic film Kedarnath, in which she played a Hindu girl who falls in love with a Muslim porter, played by Sushant Singh Rajput. In preparation for her role, Khan improved her knowledge of Hindi vocabulary with help from Rajput. Kedarnath received mixed reviews with praise directed to Khan's performance. Kunal Guha of Mumbai Mirror found it to be a rehash of 1980s Hindi films but appreciated Khan's act: "When her Mukku is angry, hopeful, desperate or coltish, she often conveys it through her eyes alone — giving us a taste of the diverse faces she can throw on." Meena Iyer of Daily News and Analysis similarly labelled her "spectacular". Kedarnath emerged as a commercial success with a gross of over ₹960 million (US$10 million). Khan was awarded with the Filmfare Award for Best Female Debut and the IIFA Award for Star Debut of the Year – Female.
A few weeks after the release of Kedarnath, Khan starred in Rohit Shetty's action film Simmba, alongside Ranveer Singh, which was loosely based on the Telugu-language film Temper (2015). She began work on it when filming of Kedarnath was temporarily suspended. This led to Abhishek Kapoor suing Khan; they later settled out of court when she agreed to split her time between both films. Reviewing the film for The Times of India, Ronak Kotecha opined that Khan had "precious little to do besides looking breathtakingly beautiful" and disliked the chemistry between her and Singh. With worldwide earnings of ₹4 billion (US$42 million), Simmba emerged as the third highest-grossing Hindi film of 2018.
In Imtiaz Ali's romantic drama Love Aaj Kal (2020), a spiritual successor to Ali's 2009 film of the same name, Khan starred as a young woman with a troubled past, opposite Kartik Aaryan. In a negative review of the film, Nandini Ramnath of Scroll.in bemoaned that Khan "simply doesn't have the experience or the expertise" to play a complex character, adding that "having a camera shoved into her young face only enlarges her shortcomings". It emerged as a box office bomb. In the same year, Khan starred opposite Varun Dhawan in the comedy film Coolie No. 1, an adaptation of David Dhawan's 1995 film of the same name. The film had strong viewership on Amazon Prime Video but it was unanimously panned by film critics. Khan was criticised for not adding any value to the film, with Anna M. M. Vetticad of Firstpost opining that Khan does nothing more than fill the slot of "the hero's love interest".
In 2021, Khan featured as a woman with post-traumatic stress disorder in Aanand L. Rai's drama Atrangi Re, co-starring Akshay Kumar and Dhanush, which premiered on Disney+ Hotstar after multiple delays due to the nationwide lockdown due to the pandemic. The film received mixed reviews from critics. Monika Rawal Kukreja of Hindustan Times called her the "soul" of the film and praised her acting range and her Bihari accent. Conversely, in his review for Mint, Uday Bhatia criticised her "grating Bihari accent".
