Sci-fi is just science fiction, not future. Space and high tech are normal for the genre, but I did a comic that was "steampunk" in nature. Set in the early 1800s with technology that doesn't exist and sure, eould be impreasive even today, but I wouldn't call typically "advanced".
Remember, even Frankenstien is sci-fi and in the books it's not even mentioned how the dude brought the monster to life. The whole "It's alive!" And lightning was made up for the movie. Everything besides the living collection of corpse parts is super grounded in the times.
And some people even argue The Mysterious Case of Dr.Jekyll and Mr.Hyde is sci-fi too-- and in that one the only "tech" is a potion that changes the dude's appearance so he can go do devious things without it being connected to his good doctor name. Granted, that's just what some argue it is just labled gothic fiction hah;
Point being, just like fantasy sci-fi is SUPER vast. Where people recognize fantasy as being more than just "lord of the rings" with its many subgenres, less seem to think that way about sci-fi for whatever reason.
Don't get too caught up thinking sci-fi has to be futuristic or super high tech haha; chances are, if it's dieselpunk it's sci-fi.