Hi…
An new frame style named “Heading inline” was introduced in 25.2 . The justification is in the link below.
As far as I tested, it is a inline frame style to handle a heading-styled content in the paragraph.
https://git.libreoffice.org/core/+/7a35f3dc7419d833b8f47069c4df63e900ccb880
Cheers
Olivier