In the movies, Morgan Stark is the 5-year-old daughter of Tony Stark and Pepper Potts. Her role in the movie was mainly to show Tony finally getting a happy family. The family he would risk losing when he would help fight the battle against Thanos. She showed some interest in playing around with technology but that is all. No other hints for her future in MCU.
However, the Morgan Stark we come across in MCU is very different from the Morgan Stark in the Comics. In the Marvel comics, Morgan Stark is Tony’s cousin. He is the son of Edward Stark, Howard Stark’s brother making him Tony’s uncle. Edward gave away his share of the property (willingly) to Tony. This left cousin Morgan with nothing but jealousy.
He tries to bring Tony down in many times allying himself with different people who want the same thing, Tony Stark aka Iron Man down. Summarizing, the Morgan Stark we see in the MCU and in the Comics are very different.
In Infinity War, Tony dreamt about having a son with Pepper and naming him Morgan. Maybe the MCU introduced Morgan to see Tony’s dream come true. Or maybe Morgan has an actual future as the successor of Iron Man. But it is most definitely not something in common with the comics.