assign value to a variable using eval in a metaprogramming manner

If you're outside a function you can use

globals()[varname] = value

Example:

>>> a
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'a' is not defined
>>> globals()['a'] = 5
>>> a
5

Inside a function there's locals() but it can only read from the symbol table and not update so you should use eval() like other answers have pointed out.

You can also cheat by using setattr/hasattr/getattr on an object:

>>> class Object:
...     pass
... 
>>> obj = Object()
>>> obj.a
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'Object' object has no attribute 'a'
>>> setattr(obj, 'a', 3)
>>> obj.a
3

does exec accomplish what you're trying to do?:

sample = None
var_name = "sample"
value = 5
exec(f"{var_name} = {value}")

print(sample)

output: 5