In the below image, the Record Generator is used as the source step in this example.
Illustrated in the below image is the data that is populated in the Record Generator step. Highlighted in yellow is the first letter of the value which is in a lower case.
The image below contains the code that is used in the Calculator step to convert the first letter of a value to an upper case using handlebars. Highlighted in yellow is the name of the field that contains the values that you want to capitalize.
Illustrated in the below image is the output where the first letter of the value is in upper case/ capitalized.
Additional information on handlebars: