You can change the vertical alignment of text in Affinity Publisher — I spent a little too long looking for the right thing in the Paragraph and Character panels. What you want, is the ‘Text Frame’ panel (from the menu, go to View > Studio > Text Frame). From there, click on he ‘Vertical Position’ section (if it’s closed), and then click on the icon with the alignment you want.
Vertical Align Text in Affinity Publisher
By Forrest Smith - Drempd.com