GoLand can complete statements and add required trailing commas for any composite literals (like struct, slice, etc.), and even place caret in a position where you can just start typing the next statement.

How to use:

After typing parentheses, trigger the Complete Current Statement action, ⌃⇧⏎ (macOS) / Ctrl+Shift+Enter (Windows/Linux), to add curly braces and move ethe cursor down to the beginning of the next row.