One method is to use a garment steamer. Simply hang the flag flat and gently apply steam to the wrinkled areas until they relax and flatten.
Another alternative is to either hand or machine wash the flag in cold water, followed by hang drying. The washing process usually eliminates wrinkles, and by hanging it flat to dry, you prevent new ones from forming. However, it's crucial to ensure the flag is color safe first.
You can test the flag's colorfastness by rubbing a cotton swab on the colored areas. If any color transfers onto the cotton swab, the flag is not color safe, and washing it should be avoided.
If your flag passes the colorfastness test, you can regularly use the washing method to keep it wrinkle-free.
Remember, a garment steamer is an excellent tool not only for de-wrinkling flags but also for everyday clothing. Its convenience and effectiveness make it a great alternative to ironing.