A new article on the site GalaxyClub claims that the 5G variant of the upcoming Samsung Galaxy S10 line will have the series' largest-ever battery. Much like the rumored Galaxy M20, It will have a capacity of 5000mAh. This possibility would mean that even the Galaxy Note 9 would no longer have the largest battery of any Samsung flagship.
https://www.notebookcheck.net/New-report-asserts-that-the-Samsung-Galaxy-S10-5G-will-come-with-a-5000mAh-battery.393581.0.html