What do you mean with your phone "reacting as a trigger"? Do you mean location/presence? If so, the natively supported option is Life360, but you can unofficially integrate some other options (like HomeBridge for iOS presence). These aren't strictly Wi-Fi, but maybe that's what you want. I see the above post does mention a Wi-Fi only option along with reasons that isn't necessarily 100% reliable. The forthcoming Hubitat mobile app should also support presence, but there is no timeline for that. Or maybe you want something else entirely--I'm not sure.
As for how to automate your lights in the way you ask, it depends on what you want. Rule Machine would certainly be the most versatile option, but it may be a bit more difficult to set up if you're new. Hubitat Simple Lighting may work if your presence sensor (if that's what you're talking about) is exposed as a (virtual) switch, since I don't think it natively supports presence itself.
For Dashboard, you can use Hubitat Dashboard for a natively supported options. The docs are here and are probably a better place to start than me trying to regurgitate information about the app: Hubitat® Dashboard - Hubitat Documentation. You can create the dashboard on any device, but if you at least begin the process on your phone, I think it will automatically choose a size that works well for your screen size/resolution. (Honestly, I'd find editing easier on a desktop easier after that.) There are also third-party options like SharpTools.io (natively supported but cloud-only and with a limited free tier).
I mean a presence/location trigger.
In my ignorance I thought it was implemented in the hub.
I have an android phone but we have 2 Android and 2 iPhone in my house and it would be nice if say, all phones was out of the house, the hub would trigger a "all lights off roule". That's my goal.
Easiest and most supported method currently is to use the free Life360 App on each phone, and then add the built-in Life360 App within your Hubitat hub. This will create a "Presence" device for each phone. As they come and go from your home's geofence, the status of each presence device will be automatically updated.
With Life 360 after you have it setup on each phone and everyone in the same circle you have to create a place for your address which then lets you choose the geofence radius then you use that place in your setup of the Life 360 built-in app in Hubitat.