Hi dsammied,
No. However, you could list all User rows whose name equal Sarah Willis. Then update the row. Please follow the steps:
1. List all rows whose name equal the Sarah Willis

2. Check the length is 1 or not.

3.If yes, then update your row. Owner's expression: concat('systemusers(',first(outputs('List_rows')?['body/value']).systemuserid,')')

Test:
