Hi @KelseyVisc ,
I see what you mean, please check out this test.
In Get items, I'm using Title (the column where I store my name) eq 'Name' to filter out the information of people who already exist in the list, if length(outputs('Get_items')?[' body/value']) is greater than 0, it proves that the person has been created in the list, if it is equal to 0, it proves that the person's record does not exist, and a new record is created.

length(outputs('Get_items')?['body/value'])
Note: When you are in a Filter Query, remember to filter with the name of the column in your list.
Best Regards,
Sunshine Gu