I believe they are currently still working on this. You can check the roadmap for next-gen here: https://www.atlassian.com/software/jira/whats-new/next-gen#intheworks
Under "Enable everyone on the team to personalize their view of the board", they mention swimlanes and it should be coming in 2020.
Hope this helps
I'm afraid waiting is all you can do for now.
I'm not on Cloud myself, but it's possible that swimlanes are already available with the "Group by" selection in the right upper corner. If the option isn't there, then I assume it's still in development.