Not sure there is anything which will do it automatically - a ticket printer is just a specific format printer after all - but there is the
PrinterSettings.PaperSizes Property (System.Drawing.Printing) | Microsoft Docs[
^] which returns a collection of supported paper sizes. Presumably, the ticket printer will support specific sizes rather than A4, A3, etc.
PrinterSettings ps = new PrinterSettings();
Console.WriteLine(ps.PrinterName);
foreach (PaperSize paperSize in ps.PaperSizes)
{
Console.WriteLine("{0}: ({1}, {2})", paperSize.PaperName, paperSize.Width, paperSize.Height);
}
Gives me these for my Epson BX305:
EPSON4782F5 (Epson Stylus Office BX305)
A4 210 x 297 mm: (827, 1169)
10 x 15 cm (4 x 6 in): (400, 600)
13 x 18 cm (5 x 7 in): (500, 700)
A6 105 x 148 mm: (413, 583)
A5 148 x 210 mm: (583, 827)
B5 182 x 257 mm: (717, 1012)
9 x 13 cm (3.5 x 5 in): (350, 500)
13 x 20 cm (5 x 8 in): (500, 800)
20 x 25 cm (8 x 10 in): (800, 1000)
16:9 wide size (102 x 181 mm): (400, 711)
100 x 148 mm: (394, 583)
Envelope #10 4 1/8 x 9 1/2 in: (413, 950)
Envelope DL 110 x 220 mm: (433, 866)
Envelope C6 114 x 162 mm: (449, 638)
Letter 8 1/2 x 11 in: (850, 1100)
Legal 8 1/2 x 14 in: (850, 1400)
A3 297 x 420 mm: (1169, 1654)
A3+ 329 x 483 mm: (1295, 1902)
A2 420 x 594 mm: (1654, 2339)
B4 257 x 364 mm: (1012, 1433)
B3 364 x 515 mm: (1433, 2028)
User Defined: (827, 1169)