I was able to gain a new perspective through this lesson.
I was able to learn something new that I never knew before this lesson.
ご質問ありがとうございます。
この場合、「I was able to gain a new perspective through this lesson.」と言えます。
特に、視野を得られた事に関して、この表現は適切だと思います。
また、別の言い方で「I was able to learn something new that I never knew before this lesson.」にも言えます。この英文にて「learn」の代わりに「discover」でも構いません。そうすると、「I was able to discover something new that I never knew before this lesson.」で結構です。
ご参考になれば幸いです。