I've watched some tutorials on creating timer jobs and they seem to use serverside code, which from what I understand cannot be used with SharePoint online hosted on a Microsoft Server. Is there any way to create a Timer Job to run custom code on a Microsoft hosted SharePoint Online server? Thank you.
No, no timer jobs in SPO due to being FTC. That said, in certain scenarios there are alternatives, such as Azure Web Jobs, Webhooks, and so forth. Here's an older example of building an Azure Web Job as a replacement for a timer job.
Others might have newer examples that are more relevant to today's models.
full trust code are not supported in SharePoint Online environment.But we will use the Azure WebJobs and PowerShell CSOM script.
What's in the script Sample script written with PowerShell CSOM, connects to SharePoint site using CSOM and creates an item in a custom list. It uses the user context of the given credentials in the script, it can be treated just like a service account. Update the site url, username, and password section in the script.
Download full code from Gallery: Azure WebJobs (Timer Jobs) for Office 365 SharePoint Online