Aspose.Cells does support to convert Excel files to PDF directly, see the topic for your reference:
Also, to create PDF files by Aspose.Cells would be based on Excel workbook. For example, you may create a new Workbook, fill data, apply style/formatting, then finally save to PDF format. This is the process.
See some topics in the section/sub-section that may help you to apply formattings to cells/range of cells etc.: