Lenovo M8 FHD – how to enter service mode on a ‘wifi only’ device?

Apparently theres this thing called ‘service mode’ or ‘engineering mode’ for most / some / all ? devices. Was news to me, can anyone tell me how to access this on the titled tablet without a dialer (wifi only).
Many thanks!

I tried app store – MTK engineering mode – says its made for previous versions of android – may not work, why nothing since, it was released late 2019 (or am I missing some big event!) Maybe Lenovo changed their service policies or this is to do with ‘treble project?