Boba Fett's color scheme isn't the most attractive combination of colors, but it has become such an iconic staple of his character that it's hard to imagine him wearing anything else. Just as Din Djarin has become known for his shiny chrome armor, Boba Fett's armor always stays in a similar color scheme, no matter how many times it's repainted.
In Mandalorian culture, red is meant to honor the wearer's parents. A huge part of Boba Fett's backstory is his relationship with Jango Fett. Jango is the person the clones are based on. One of his stipulations for his cooperation is being given a clone that will age at a normal rate. That clone is Boba, who he treats like a son.
Jango's death at the hands of Mace Windu (Samuel L. Jackson) shapes Boba for many years, so he always wears red to honor the bond he shares with his father. The gold in his armor also represents his desire for vengeance for his father's death.
Likewise, green, which is the main color in his armor, is meant to represent duty. Although Boba has been a bounty hunter for many of his appearances, he has also taken on some pretty important roles over the years. For instance, he serves as both a Journeyman Protector and the Mand'alor in "Star Wars Legends."
