I need to install an app but it shows an untrusted dev message I need to find where to trust the dev please

I’m trying to install an app but it says developer untrusted, I need to install the app and I do know the developer but I can’t find where to trust the developer, I’ve already looked in google but it says to look for it on settings-general-profile… etc but it is not like that on my phone I have an iPhone 8 can anyone help me with that???