Function to display heart rate verticaly?

I would like to have the heart rate displayed verticaly, for example instead of 114 i would like to display

I hope, someone who is an expert with functions might be able to help

Maybe you can use bitmap fonts?

Rotate your text layer by 90°. Then add bitmap fonts - rotate characters by -90°

Easiest would be to use a rotated (vertical) font and turn the text field 90°.
Making own rotated bitmap font like suggests @amoledwatchfaces might be easier than finding such font already made to your liking. Here is a fancy example:

Or you can split the text in 3 text fields and compute each digit separately. for example like this: