Changing the inscription depending on the selected city?

Question

PHP

It is necessary to make a substitution of the inscription if the city of St. Petersburg is selected.
This is what the button looks like

<a class="link-dotted-invert" href="" data-zone-dialog-trigger="">
    <span data-zone-current="" data-ng-bind="zone.City" data-start-val="{City: 'Санкт-Петербург'}">Санкт-Петербург</span>
</a>

In the browser cookies in ipzone there is the selected city in krakozyabra, if you decrypt it, it turns out 171; 58; 781; St. Petersburg; St. Petersburg in the project files found 2 files: zones.json and cities.json, they contain all the cities. Here for St. Petersburg

{ "CityId": 781, "Name": "Санкт-Петербург", "RegionId": 58 },

You need to make sure that when you select SPB, the inscription changes.
How will the condition approximately look like that, if CityId is 781, then we display our own inscription, if not, then the standard one?
Or at least where you can read about it?