How to change the Apple ID and keep everything from the previous ID ?

Yes, if you do it this way:

1. Go to https://appleid.apple.com and sign in.

2. In the Sign-In and Security section, choose Apple ID.

3. Enter the email address that you want to use as your Apple ID.

4. Choose Change Apple ID.

5. If you changed your Apple ID to a third-party email address, check your email for a verification code, then enter the code. Learn what to do if you didn't get the email. --> https://support.apple.com/kb/HT201455

6. If you use services like iCloud or Messages to share with friends and colleagues, sign in to those services with your updated Apple ID. --> https://support.apple.com/kb/HT204071

For more details, read the document: "Change your Apple ID" --> https://support.apple.com/HT202667

If Apple tries sending you a verification email and you do not receive it, read this support article --> https://support.apple.com/HT201455

"When you make certain updates to your Apple ID, we’ll send you an email to help you complete the update. For example, you might have reset your password, reset your security questions, or added a new email address to your account."

If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (go to this document: https://support.apple.com/kb/HT204921 ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity.

From:

Change your Apple ID - Apple Support

- There's special instructions if you want to change your Apple ID to an @icloud.com address.

"If you try to change your Apple ID to an @icloud.com email address that was created within the last 30 days, you will be asked to try again later."