I lost my iPhone 8, how can I sign out my apple id account from the phone

Consider reading this Apple technical support topic: https://support.apple.com/en-us/HT210515

This link might help... 👉🏼 https://support.apple.com/en-us/HT208242

I suggest you lock the phone.

If you remove your Apple ID and turn of Find My Phone, whoever finds the phone will have complete access.

Find My Phone - Lock and track your device using Lost Mode.       

Find My Phone - If your device is lost or stolen.