The history of large phones, from a technical standpoint:

• LTE required a lot more power than 2G/3G until efficiencies were improved, this required a larger battery to have comparable battery life, doubly so on the phones that ran two modems (mostly Verizon) one for 3G, one for 4G
• LTE required larger antennas as their low band frequencies were lower than previous cellular tech. (750MHz and later 600MHz vs 850MHz being the old lowest)
• Handset manufacturers then stopped making smaller product lines even after efficiencies improved
• People ("consumers") realized they'd rather not buy a phone, tablet, watch, computer, anal implant, and preferred to just buy one device, settling on an oversized phone was enough between phone/tablet that they only needed to waste money on one device
• The market then went, "people prefer larger phones," even though smaller phones were waning/outliers
• Tablets outside of Apple's ostensibly died, although there are a few more choices these days that aren't Apple
• Now phones have so many antennae
  • WiFi/BT (which are often shared)
  • WiFi 6 new band
  • NFC
  • Wireless charging coil
  • Ultra Wideband
  • 20 or 30 various cellular bands with 4x antennae for MIMO
  • mmWave (in America)
• Phones also have gigantic camera systems (although since Samsung gave up on 10x optical, they shrunk slightly on that platform)
• The cycle repeated itself a bit with 5G, the channels are so wide and huge, they can suck a lot of power when doing large data transfers, and also the addition of needing a separate amp/chip for 5G above sub6 as well as additional cooling
• "AI" stuff that requires more ML compute, and thus cooling and battery capacity, even though again, nobody wanted it
• All the metrics and analytics handset manufacturers constantly run on users, disabling all this alone would probably make your average phone last 3+ days

Since then, more and more people are trying to get flip phones, dumbphones, imported small phones, or giving up on phones entirely and switching to devices like the Lilygo T-Deck LoRaWAN device that has...dun dun dunnnnn....a literal BlackBerry keyboard, as people are sick of that fabled market deciding for them.