Control spacing between nested styles with line break

The quick answer to your specific question is Basic Character Formats > Leading.

But like Bob suggested, I’d change the line break to a paragraph break and define two paragraph styles. Then you can add spacing below Title or above Subtitle.

This should absolutely be two paragraph styles.

The space before the second line should be done by increasing the leading in the character style which you are applying for the second line. Since a nested style exists within a paragraph style you cannot do this with space before or space after.

Control the space with leading as always.

You have probably over complicated this with the forced line break. This is a use for Next style.

Studio Name char style should be a Para style and define a next style as light with a single nested of regular through 2 digits