In the Style Manager dialog, label settings tab, select an item
Right-click and "copy item"
Right-click and "paste item"
Fill in the form that opens and OK
Where is your new item? Check the "Text format" tab. It's there and unfortunately, with only the compatible properties

| QGIS version |
3.17.0-Master |
QGIS code revision |
1b56825 |
| Compiled against Qt |
5.12.8 |
Running against Qt |
5.12.8 |
| Compiled against GDAL/OGR |
3.0.4 |
Running against GDAL/OGR |
3.0.4 |
| Compiled against GEOS |
3.8.0-CAPI-1.13.1 |
Running against GEOS |
3.8.0-CAPI-1.13.1 |
| Compiled against SQLite |
3.31.1 |
Running against SQLite |
3.31.1 |
| PostgreSQL Client Version |
12.5 (Ubuntu 12.5-0ubuntu0.20.04.1) |
SpatiaLite Version |
4.3.0a |
| QWT Version |
6.1.4 |
QScintilla2 Version |
2.11.2 |
| Compiled against PROJ |
6.3.1 |
Running against PROJ |
Rel. 6.3.1, February 10th, 2020 |
| OS Version |
Ubuntu 20.04.1 LTS |
This copy of QGIS writes debugging output. |
|
| Active python plugins |
db_manager; MetaSearch; processing |
|
|
In the Style Manager dialog, label settings tab, select an item
Right-click and "copy item"
Right-click and "paste item"
Fill in the form that opens and OK
Where is your new item? Check the "Text format" tab. It's there and unfortunately, with only the compatible properties