How to share wifi to another device

Probably you mean share Wi-Fi password.

How to share your Wi-Fi password

1. Make sure that your device (the one sharing the password) is unlocked and connected to the Wi-Fi network.
2. Select the Wi-Fi network on the device you want to connect.
3. On your device, tap Share Password, then tap Done.

How to share your Wi-Fi password from your iPhone, iPad, or ...

Do you mean that you want to set up a hotspot? If so, this link should help:

How to set up a Personal Hotspot on your iPhone or iPad – Apple Support (UK)

Good luck.