Yes. Ranma and Shampoo in Shampoo's Red Thread of Dread and Earth of Shampoo - Episode 13 - Shampoo and Ranma animals friends everywhere! your love life are ever had.

In episode 15, though technically Ranma had met Shampoo in China before when he and his dad was training before coming to the Tendo Dojo but she makes a reappearance in episode 15, looking for Ranma now.

Episode 15.

You can read Ranma and Shampoo fanfiction on websites like FanFiction.net and Archive of Our Own (AO3). These platforms have a wide range of fanfiction stories based on various characters and pairings from the Ranma ½ series.

Shampoo makes a re apparence at the end of the first season, she bursts in the house looking for Ranma.

In the manga, Shampoo doesn't appear until Volume 4. So the Anime put her in early, if that helps the confusion.

Though. Ranma met her once in China before coming to Nerima being the reason she is hunting him down in the first place.