SPX 500 Monthly Return Google Finance

I need to formulate the SPX500 return from "x start date" to "x end date".

I have managed to figure out "x start date" to current date (year to date return) but I cant work out how to do historical to fixed date.

Here's what I have thus far for year to date yield.

I need to work out returns from 1/1/21 to 31/1/21 for the S&P500

=(googlefinance("INDEXSP:.INX","price")/index(googlefinance("INDEXSP:.INX","price",date(2021,1,1)),2,2)-1)