Change size of dashboard

good day all,

I want to display some information on a tablet.
I created a dashboard and a user that only has access to that dashboard.
however everything is so small that it is unreadable.
when I zoom the webpage there are 2 columns readable.
however the interface shows 3 columns. and at every restart the zoom is gone.

is there an option to change the size for one user/dashboard/device.

for the other users, dashboards or devices the normal size is fine.

Many thanks for the effort.
Mark