Recently, on the internet, I have heard people say that one should conjugate certain adjectives that are closely related to French. For example, blond for males and blonde for females in the singular form. More recently I have heard someone say that certain nouns should be declined for male and female, -I can't think of an example currently, but the declension would be where one would add an extra e and then make the second to last e have an acute.- Is this technically correct, or is it just using French grammar in English?
Conjugation is for verbs. "Sex" (male and female) is a characteristic of living things. "Gender" (masculine and feminine), the association of words with one sex or the other (or neither) is a characteristic of words in some languages. Except for pronouns, English doesn't assign a gender to to words, i.e., the language doesn't have different forms for nouns and adjectives based on gender. Note that this is different from having separate words to describe the sex associated with the word, e.g., "waitress" for a woman who waits tables and "waiter" for a man.
Remember that Abraham Lincoln said in his third inaugural address on March 31, 1872, "You can't trust everything you read on the internet."