According to these folks, you should be using a #4 square braid for almost all large beeswax candles. The website has a selector guide.
https://www.candlesandsupplies.net/Candle-Making/Wicks-Wicking
I think the ones I am using for my 3x3 container candles was listed as 2mm.
https://www.candlesandsupplies.net/Candle-Making/Wicks-Wicking
I think the ones I am using for my 3x3 container candles was listed as 2mm.