In some games, it may be possible to paint the wings as part of a larger skin or livery customization. However, if the PSD files provided by the game’s developer do not include the wings or winglets, it may not be possible to paint them separately.
As for your second question, it’s possible that the 737 MAX 8 engines can be obtained as a separate add-on or mod. You may want to search online forums or marketplaces specifically for add-ons or mods that include the MAX 8 engines. Adding them to the game can vary depending on the game and the mod, but it may involve replacing the existing engine model files with the new ones. Again, it’s important to carefully read the installation instructions provided with the mod to ensure it is installed correctly.