Is it possible to install the Android browser and email app if they weren't built-in? As far as I know, older Android tablets/smartphones have the Android web browser and email app as their built-in web browser and email app.

But my Android smartphone does not have those. My Android smartphone's built-in web browser and email app are Google Chrome and Gmail. I guess that is because the version of Android OS of my Android smartphone is a bit newer (Android 7.0).

Is it possible for my Android smartphone to install the Android web browser and email app?
Stock Android browser and email app were discontinued since KitKat :


Google puts Android’s stock e-mail app in the Play Store
Android 4.4+ KitKat ships without browser app. OEMs have to license Chrome or build their own


They have been replaced by Gmail and Chrome as commented. Even if you are willing to face security risk to have it installed you can't downgrade from Nougat to KitKat (extremely unlikely). Only option left is to run a device of pre KiKat OS having those stock apps