as for the project title you cant mix different styles
but you can use project descriptions and mix different styles in there:
https://laytheme.com/documentation/project-description.html
if you want to use textformats for mixing different styles within one line or one word, its best to use a format type of "character"
Screenshot 2023-09-04 at 15.50.56.png
because the other formats will create new blocks of text
