This is available for Pro a/c only on TV, just like vol Profile etc. If you check the symbol here:
https://www.tradingview.com/x/43dqXP9R/ on top left hand corner, this is a ratio chart of BANKNIFTY/NIFTY, likewise I can do any of the math + - / x or 1/ (inverse chart) -
https://www.tradingview.com/x/iwzKK17a/ (sometimes helps in seeing the chart from other end) or any 2 symbols available
https://www.tradingview.com/x/hQo2pk5w/ (NIFTY in dollar terms)
This function is very useful for this kind of ratio analysis or in case of options, I can easily plot straddle/strangle charts, by giving two symbols, lets say:
NSE:NIFTY18JUN10700CE+NSE:NIFTY18JUN10700PE (TV does not have NSE FO data, hence I cant
)