List view Threshold Limit office 365 SP online

Hi Guys,

Am stuck with threshold limit can you help me, am using sharepoint online enterprise version, our list/library about to hit 5000 items, right now it was 4500 items. It showing the graphical bar in library settings. (cannot be increased threshold limit in SP online)

How do i overcome this issue we use record centre template to store recored/documents. one of the library has this problem. I tried few things research on google found the below article.

https://support.office.com/en-gb/article/Manage-large-lists-and-libraries-in-Office-365-b4038448-ec0e-49b7-b853-679d3d8fb784

managing list/libraries , indexing columns,modifying view can only  reduce the performance issues. how about the upload documents. I heard that sharepoint online throws error message and restrict the documents to upload,If items reach to max limit. How do i resolve this?

Thanks,

Manoj.