Hi there tjameswhite,
Thank you for using the Apple Support Communities! We understand you just purchased your iPhone SE (2nd generation), but you're not finding a way to use 3D Touch, like you had on your iPhone 7. We can help address this concern.
Taking a look over this article Change 3D or Haptic Touch sensitivity on your iPhone - Apple Support, it states the following,
"These devices support Haptic Touch: iPhone SE (2nd generation), iPhone 11, iPhone 11 Pro, iPhone 11 Pro Max, and iPhone XR. These devices support 3D Touch: iPhone 6s, iPhone 6s Plus, iPhone 7, iPhone 7 Plus, iPhone 8, iPhone 8 Plus, iPhone X, iPhone XS, and iPhone XS Max."
3D Touch was replaced with Haptic Touch on the iPhone SE (2nd generation) model. With Haptic Touch, you can still long press on app icons, or items on your Lock screen. Head over to Settings > Accessibility > Touch > Haptic Touch, and choose from 'Fast' or 'Slow' to see which option you prefer.
When viewing notifications specifically from the Lock screen following the steps in Use notifications on your iPhone, iPad, and iPod touch - Apple Support, Haptic Touch is not supported on this model of iPhone. You can manage your notifications using the following steps instead:
"On iPhone SE (2nd generation), swipe left on the notification, then tap View to see the notification and perform any quick actions that the app supports."
Feel free to leave feedback for Apple, as well: Product Feedback - Apple.
Best regards.