Hello there Realme U1 users,
UI Version: RMX1831EX_11_C.19
Security
● Android security patch: May 2020
System
● Fixed some known bugs, and improved system stability
Also, read this note from developers.
Note: In order to ensure the stability of this update, it will have a staged rollout. The update will be randomly pushed out to a limited number of users today and will have a broader rollout in a few days after making sure there are no critical bugs. If no critical bugs are found, the full rollout will be completed in the upcoming days.
Go to settings>Software Update and check for update. If available then click on update and enjoy.
The manual link will be available on their website soon.
Source:-Realme Community