Initially, sequels attract the audience due to their title, which demonstrates brand value. But if the content of the sequels is not good, the film will fail at the box office. In other words, if the prequel is good and the title registers in the minds of the audience, they will watch the sequel but if the content is not strong enough, the film will not survive.
Sequels have the advantage of their titles being familiar to the audience. So when a sequel is released, people connect to the film. But the audience always expects more from a sequel. If they were happy with the last film of the Sarkar franchise, they will definitely watch Sarkar 3. The content of the film matters a lot. For example, Kahaani did well at box office because of its content but Kahaani 2 did not do as well as the first part did.
By default, sequels used to benefit from the success of the original film, even if they weren’t organic extensions or a natural progression of the story. But now sequels work based purely on their content. Also, the star cast of the film matters but if the sequel is lacking in content, it is bound to fail.
According to me, if the prequel impressed the audience, they will watch the sequel. Producers are now spending large sums of money on sequels in an attempt to make them bigger than the previous part, as in the Bahubali franchise. Apart from that, good content works wonders, as is evident from films like Jolly LLB 2, which worked because of its content. I believe Badrinath Ki Dulhania will do well because the first part connected quite well with the audience.