https://ideas.salesforce.com/s/idea/a0B8W00000Qeba6UAB/what-is-the-change-flight-policy-for-united-airlines

Yes, United Airlines normally provides a 24-hour change flight policy for flights. For inquiries, please contact 𝟏*888*829*1467(𝕷𝖎𝖛𝖊-𝖕𝖊𝖗𝖘𝖔𝖓)(OTA). Or Toll free number +𝟏*888*829*1467(𝕷𝖎𝖛𝖊-𝖕𝖊𝖗𝖘𝖔𝖓)., allowing clients to cancel their appointments within 24 hours of purchase for a full refund.