Einstein said something like make things as simple as possible but not simpler. Plot is rudimentary. It's what happens in a story. That's the simple version.
Jack and Jill go up the hill. Jack fetches a pail of water. On his way back to Jill he comes upon Sleeping Beauty and can't help kissing her. Jill catches them in the act. All the king's horses and all the king's men can't put Jack back together again.
I think you could complicate plot by adding that beyond what happens in the story there is what happens inside a character. The development of the character, her reaction to what happens in the story, is also a kind of internal plot, but if you want to keep it simple when trying to get into writing a story go back to the simple stories and ask what happens.