here is how to https://docs.djangoproject.com/en/4.0/howto/custom-template-tags/

django template filter to convert english text in benglai

@register.filter()
def to_bengali(value):
    string_value = str(value)
    bn_digits = {
    0: '০',
    1: '১',
    2: '২',
    3: '৩',
    4: '৪',
    5: '৫',
    6: '৬',
    7: '৭',
    8: '৮',
    9: '৯',
  }

    for x in bn_digits:
        string_value = string_value.replace( str(x), bn_digits[x] )
    return string_value