With calculated fields, you can create new metrics and dimensions derived from your data. Calculated fields let you extend and transform the information flowing from your data sources and see the results in Looker (formerly Google Data Studio or GDS) reports.
Learn how to create your own formula
For more help with calculated fields, please visit https://support.google.com/datastudio/answer/6299685?hl=en#zippy=%2Cin-this-article