I have tilesets that are changing very constantly and i was wondering what is the best way to configure for tileset expansion? I know that tiled re-adjusts the index if a tileset expands in width and height but should i just pre-define a large tileset? e.g, make the width 2048(max texture size for webgl) and then gradually fill it in? Or is this not an issue for tiled at all and i can just do what i want?
While Tiled does try to adjust to a change in width, I would still try to avoid it. The adjustment is still not entirely unproblematic, for example if several maps use the tileset, only the maps that are open are adjusted. This means that to do it right, you may need to open all maps using a certain tileset in Tiled and only then resize the tileset image.
Adjusting to a change in height is much easier since it does not require remapping the tile IDs. So while you should ideally start your tileset using your target width, the height can be kept as low as possible and can be changed without needing any adjustment in the map files.