Can I get a 30-day extension after a border run to Mae Sai with a Visa Exempt Entry?

I’m heading off to Mae Sai next week for a boarder run – first time.

After returning to CM, can I then get a 30 day visa extension – like I did after arriving by air?

Like so …….

* Initial arrival by air > 30 day VOA

* Then 30 day extension at CM Immi – done

* Boarder run to Mae Sai > another 30 days (is this a VOA ?)

* Another another 30 day extension at CM Immi ?? This is my main point of concern

* Depart by air – total stay of 120 days

Many thanks people