How to format raw string with different expressions inside?

Use f-strings (introduced in Python 3.6):

a = 15
print(fr'Escape is here:\n but still {a}')

# => Escape is here:\n but still 15

Escape the curly brackets with curly brackets

>>> import re
>>> text = '"""!some text'
>>> re.findall(r'"{{3}}{symbol}some\stext'.format(symbol='!'), text)
['"""!some text']

However it is better to just use % formatting in this situation.