l10n_forms.py

class PlanForm(forms.ModelForm):
    
    class Meta:
        model = Plan
        fields = ("price", "title", "description")
        
    def __init__(self, *args, **kwargs):
        super().__init__(self, *args, **kwargs)
        self.fields["price"].localize = True
        
# settings.py
USE_L10N = True
DECIMAL_SEPARATOR = ','
NUMBER_GROUPING = 3
USE_THOUSAND_SEPARATOR = True
THOUSAND_SEPARATOR = '.'