The only way I’ve figured out how to do that is via the “Tempo” text field. It means you have to ensure the tempo is set the same but then disable it from showing, and the text characteristics are essentially disabled (or I haven’t figured out how to alter them)
I am using Notion Mobile for 95% of my work and also have the desktop version. I am not sure if there is a way to more easily do it on the desktop version or if the tempo text is the only way.