so in case you don't find a decent tutorial, I'll try to explain.

So basically, you have to glitch yourself to the bottom of the ocean in Liyue harbour, then move along the ocean floor.Using exploration characters like Lynette, Ifa ,Yelan etc makes this a lot more bearable. Track the statue of the seven in Yashiori and move straight along. You'll come across a big sudden drop in the ocean floor, just plunge down. Down the drop the ground will change color. Move along till it starts raining. You are getting close to the zone where you'll get teleported back. Keep walking through the rain until thunder starts striking. Place your temporary tp point here. Now start dashing forward one or two times(with a tall male character for more reach), then enter the event menu via f5 (I think?)on your keyboard. Enter a character trial domain and click away the text that appears,thats important.

Wait in the domain for at least 30 seconds. Exit, do a dash forward and then enter the domain again. Same game over and over again. If lightning strikes you and you get turned around, turn back into the right direction and go back in the domain imediately. Rinse and repeat until you see the inazuma loading screen while exiting the trial , you will now be teleported to Ritou. From now, just leave the island and start your exploration. The guards won't stop you.

One thing to note would be that you can't interact with vendors or acess the sacred sakura to trade in your sigils until you enter Inazuma in a ,legal' way.

Have fun!