and welcome! You can change the export file format using the Export Options panel. Pretty every file format is available here … see my screen shots. There’s also a good help topic in Help > Affinity Designer Help > Exporting.
If the Export Options panel is not already available in Export Persona, choose View > Studio > Export Options. Before exporting make sure to select your slice(s) in the slices list and adjust the export options for that (those) slice(s).
