Bluetooth version?

See it here --> https://support.apple.com/kb/SP779?viewlocale=en_IN&locale=en_IN, it says...

• All models
• Gigabit-class LTE with 4x4 MIMO and LAA4
• 802.11ac Wi‑Fi with 2x2 MIMO
• Bluetooth 5.0 wireless technology
• NFC with reader mode
• Express Cards with power reserve

Do a google search for the phone model. For example a google search for "iPhone 8 specifications" reveals this:

https://support.apple.com/kb/SP767?locale=en_US

For iPhone 7:

https://support.apple.com/kb/SP743?locale=en_US

How can I tell in settings for an older iPhone that may not be recently updated?