No such weighing service exists, you'll need to do some counting and sorting in order to help yourself. If that is something that you're not prepared to do, take them to a temple and donate them or start spending them in Tops, Lotus's, 7-11, Family Mart.
Villa in Bangkok always used to have a notice that small were wanted and they would change (and count) any quantity, Villa Pattaya may sort you out.
Alternatively, deposit them in your bank account (there may be a charge for large amounts)...https://www.thephuketnews.com/lots-of-loose-change-50403.php
Wherever you go, though, you will not be very welcome if you don't, at least, separate the coin denominations.
For future reference, as you'll never normally get more than three or four of the smaller coins in any change (no matter how hard the cashier tries) just keep them in your pocket and use them in the same shops that give them in your change, that way you'll never build up an unwanted PITA collection.