Looking for some guidance 2d or 3d turn based RPG(not the typical style need help)

Hey all, Ive recently become enamored with video game design and am currently enrolled to in classes to learn as much as i can. in the meantime i was hoping to get some help and maybe guidance down the path i am looking to go… i have a VERY clear idea of what i want, i have NO IDEA how to implement my “world” if i could just get the world layout set… i would be on my way.
i am having the hardest time finding tutorials or help in the way i need it because i believe i dont know the names of the things im looking for. any help would be GREATLY appreciated.

2D or 3D
Turn based(more of a round than a turn, character stats will determine what and how many of each action take place during each round)
Open world but only 1 screen at a time. THIS is what i do not know how to logically create inside my world. here is a link to an old old old MMORPGAA that i am being inspired by. or google “the realm online mmorpg”
i dont know how to make it so the world is real time and populated but as a player i can only see the screen i am in. the game linked above separates them into rooms, but i have no idea how to make “transitions” or bridge these together without it being diablo or skyrim open world"
i want to have to engage with the enemies and choose to initiate combat by clicking.

TLDR: help direct me to the proper terminology to create a Action Adventure turn based open world, TURN Based combat game. i can provide videos and screenshots of what im trying to do if that helps.


also im aware of the difficulties of making a mmo and all that, im not trying to make it pretty or even sell it, i just want help getting the framework down