The data type is Date or Date/Time can be set the formatting. The formatting is set by separating the field name with a comma. Available in Ver.2.0 or later.
Word/PowerPoint/PDF
e.g. {!Case.TestDate__c, MMM. d, yyyy}
Output Result ・・・ Mar. 1, 2024
Excel
Merge fields cannot be formatted. Set from Excel's cell formatting.
Instruction manual
Formatting of Date and Date/Time Fields