権限セットではできない。
Looks like this is still an idea:
Use Permission Sets to Assign Login IP Ranges
https://ideas.salesforce.com/s/idea/a0B8W00000Gdp8gUAB/use-permission-sets-to-assign-login-ip-ranges
Unfortunately there is no option to define Login IP ranges on a user or at permissions set level. As a workaround you can create a custom profile by cloning the existing one and set loign ip ranges on that and assign it to this user.