Venom co-screenwriter Jeff Pinker has gone on record stating that a Venom sequel is on its way, though he might not be the one writing it.
In an interview with Discussing Film, Pinker was asked about the possibility of a Venom sequel, saying “I can’t say anything other than that it is happening.” When asked if he would be writing the film, he replied “I am not. As of right now, I am not.”
Earlier in the interview, when asked if Tom Holland’s Spider-Man exists in the same universe as the Venom film, Pinker replied “Without revealing anything that I’m not allowed to reveal, it is not impossible that in a future/upcoming Venom movie, Spider-Man will play a significant role.”
Source: IGN.com Venom 2 Reportedly Confirmed, New Screenwriter Expected