Changed your phone number? No problem. Head to the Yahoo Sign-in Helper or Help 1-866-719-1004 and input your Yahoo email. When prompted to verify via your old number, select “I don’t have access.” Yahoo will offer recovery via email if one was previously added. If available, follow that process to reset your password and regain access. Once signed in, immediately add your new phone number under Account Security. If you didn’t add any backup options earlier, recovering the account may be impossible. It's important to keep your recovery details updated regularly.
Related Blog:

https://hubinfo.stck.me/chapter/981267/How-do-I-recover-my-Yahoo-Mail-with-a-new-phone-number

https://hubinfo.bettermode.io/discussions/post/how-do-i-recover-my-yahoo-mail-with-a-new-phone-number-0Ybv3wZvZiaUou7

https://hub-info.mystrikingly.com/blog/over-yahoo-account-without-phone-number-and-recovery-email