Download and install QGIS from the official website. I used version 3.34.3.
In QGIS, go to Plugins > Manage and Install Plugins. Search for QuickMapServices and install it.
Start a new empty project in QGIS.
In the Web menu, go to QuickMapServices > OSM > OSM Standard to add the OpenStreetMap base layer to your project. There are other base maps you can get if you go to Web menu > QuickMapServices > Settings, click on the More Services tab and install the contributor pack. Licensing/terms of use are pretty unclear for many of the contributed souces.
Zoom the map to cover the area you want to create tiles for.
In the Processing menu, go to Toolbox. Under Raster Tools, double-click on Generate XYZ Tiles (mbtiles). In the popup dialog, select "current map canvas extent" under extent. Set min/max zoom (12 min & 20 max seems good). Set the output file. Click run.