You can’t start a new character on a higher difficulty unless you have merit tokens and those you can only get by going through Elite and Ultimate difficulties with a character who can then buy them and put them in the transfer stash for your other characters to use.
To be honest I wouldn’t worry about endgame stuff atm since you’re only on Normal. Endgame is usually Ultimate difficulty Shattered Realm endless dungeon (though you can try it out in Normal if you want to) or playing Crucible.
It really depends on what you enjoy most. For me Shattered Realm and Crucible are boring so I rarely play in them, main campaign and making new characters is my thing.
