Kobo Clara HD missing beta features

I have a Kobo Clara HD and have the problem that the GUI font size is too small for me.

Apparently, there are beta features in the settings that allow a large print mode, but I don't find the beta features on my device.

I am using software version 4.37.21533 (9a4b518d5e, 6/21/23).

Can anyone help me activate the beat features or increase the GUI font size? Many thanks.