I am desperately searching for a method to lock the font size of the features displayed on the Open Street Maps base map in QGIS. Every time I zoom in the font gets so small I nearly can’t read it. And when I print the map bet on sports online https://parimatchca.com/ on A4 I barely can read anything.
Is there a way to make the label font bigger or better readable?
No, the base map is a raster map optimised for view on screen (and therefore font is too small to be readily readable on print). You will either need to create your own labels in QGIS or try & find a XYZ layer suitable for print.
For printing purposes, maybe see