How to view all app usage history on iPhone since purchase?

doubt it would waste storage space to go all the way back to the start but you can read about screen time app usage here

Use Screen Time on your iPhone and iPad - Apple Support

and

Get started with Screen Time on iPhone - Apple Support

Settings → Battery → Battery Usage by App

• Shows which apps consumed battery
• Includes screen-on and background activity
• Lets you switch between Last 24 Hours and Last 10 Days
• Timestamps like “on screen 2h 15m” help reconstruct what you were using and roughly when

Settings → Screen Time → See All App & Website Activity

• Shows apps used, time spent, notifications, pickups
• History goes back about 30 days