Approaches we can follow to run timer jobs which check some custom lists' columns and send emails

Hi All,

I have a custom list inside sharepoint online classic team site. the custom list contain a date-time field named "Project Due Date". now i want  to send an email to a group of users if the "Due Date" is within the next month.

i have not done this before on SP online, while on SP on-premises i do this by following these steps:-

1. create a console application which integrate with SP.

2. add the console application to our sharepoint on-premises server.

3. using windows task scheduler , i will schedule the console application to run on daily basis >> check the due date >> send an email to the group >> update a field inside the list item to indicate that an email has been sent (to avoid sending duplicate emails).

but of course on SP online we can not do the above 3 steps. so what are the available approaches i can follow within SP online to achieve the above requirements (check if due date is within next month >> Send an email)?

Thanks.