Help with large Sharepoint lists

Hello! I am needing some help!

I have a large sharepoint list that contains employee data. I created a PowerApp that our Suppliers use to enter the employee data in which is then fed into the Sharepoint List. We are entering approximately 3000 employees per year. 

The first issue I ran into was the 5000 entries. I created indexed columns and it seems to be working fine.

I currently have a List View for terminations. We use this view to search by the employee id and then we enter the date the employee was termed.

My question is, After the year is over, should I move the entries from the previous year into a new list so the list doesn't get so large? If I should do that, is there a way to search several lists at once so that we can still enter the terminations?