How to pass string format as a variable to an f-string

you should to put the format_string as variable

temp = f'{i:{format_string}}' + temp

the next code after : is not parsed as variable until you clearly indicate. And thank @timpietzcker for the link to the docs: formatted-string-literals

You need to keep the alignment and padding tokens separate from each other:

def display_pattern(n):
    padding = 4
    align = ">"
    temp = ''
    for i in range(1, n + 1):
        temp = f'{i:{align}{padding}}' + temp
        print(temp)

EDIT:

I think this isn't quite correct. I've done some testing and the following works as well:

def display_pattern(n):
    align = ">4"
    temp = ''
    for i in range(1, n + 1):
        temp = f'{i:{align}}' + temp
        print(temp)

So I can't really say why your method wouldn't work...