How can Apple WeChat set that it can only log in to other devices on its own mobile phone?

Yes, if the account protection function is turned on, you need to verify the mobile phone number when logging in with other mobile phones.

If you don't want to bother receiving the verification code, you can cancel the account protection function. The method is as follows:

1: First, open WeChat. There is "My Settings" in the lower right corner, click "Settings";

2: Select "My Account";

3: Click on "WeChat Security Center";

4: Select "Unlock Account";

5. Enter the verification mobile phone number-after obtaining the mobile phone verification code, fill it in.