@Dani **************
No, you can not get 90 days stamps.
How it works:
A visa is a sticker to enter Thailan, you apply normally at a Thai Consulate before you leave towards Thailand.
On entry, the Immigration checks your visa and give you a new stamp with text Admitted until .../../...
If you like to stay longer than this date you can apply for an Extension of Stay, but you must meet the requirements. You may apply year after year after year,