The ESP can act as access point and client, supposedly at the same time even (I haven't tried that - I have used it as captive portal access point though a ready-made library). So you can definitely set one up as access point - sorry, no links at hand.
That said, it sounds like overkill to me to have an ESP8266 at each sensor. It'll be cheaper and probably easier to wire the sensors - you'd have to provide a wire for power anyway (or dig into deep sleep and other power saving modes and go for battery power).
If you can provide more info on the setup (what sensors, why wireless, how's the power supply, how often are measurements taken, etc) we may be able to give you better suggestions.