No, not according to Aquinas, and traditional moral theology. You are falling prey to modern secular viewpoints.
Fornication, and even adultery observe the correct use of the sexual faculties, but in an incorrect context. Said another way, male/female intercourse is not inherently evil, just restricted to marriage.
On the other hand, masturbation, sodomy, or bestiality, are incorrect uses of the sexual faculties. There is no context in which they are not evil. Therefore, Aquinas judges them to be worse sins. I tend to agree.
Furthermore, fornication is unlike to distort one’s sexual viewpoint, while masturbation, particularly when coupled with pornography, can dement one’s reason as to sex, and lead to grave difficulties in having a correct sexual relationship within marriage.
You can find St. Thomas arguments here. Warning, he is quite dense, and requires careful reading. Remember, the “sin against nature” usually refers to masturbation, though sometimes include sodomy.
newadvent.org/summa/3154.htm
God Bless