so this is a bit complicated
first open the data.win file of the eggplant build with UTMT (wont open bc error for me) and then go to the code secton (not to be confused with code locals) and then just search "level" and a code name gml_levelselect or something i dont remember (3rd section of the code tab i think) and then enter it and it should be like
levelarray[0][0] = "ENTRANCE", 432 "entrance" (please dont shame me)
so if you like to first make a new world array called bosses (you dont have to make a new world array)
looks like this
worldarray = [6] "BOSSES" (if its wrong please dont shame me UTMT doesnt work for me)
and then make ANOTHER levelarray
leverarray [6][0] = "PEPPERMAN", boss_pepperman, "pepperman
that step is SUPER IMPORTANT and that if you dont type boss_pepperman it wont work (UTMT automatically converts it into numbers)
and save
YOU DID IT YAAAYAYAYAYAYAY
ADD MORE NEW WORLD ARRAY IF YOU WANT YAYAYAYAYAYYAYAYAYA
if its not correctly named im sorry i again DONT remember
BUT YOU DID IT YAYAYAYAYYAYAYAYAYAYYYAYAYAYAYAYYAYAYAYAYAYTAYYAYAYAAAAAAAAAAAYAYYAYAYAYAYAYAYAYAYAYAYYAAYAYAYAYAYYYYYYYYYYYYYYAYAYYAYAYAYAYAYYAA