Most isekai world have shitty excuses that solves those problems tho, no antibiotics? Healing magic!!
Isekai world have toilet as well or if we go a little more realistic then there would be roman style bathrooms.
No phones? Well there are isekai es where somehow they have Apple phones.
Or...
I don't know but most generic isekai I've seen always touch the whole racism thing, demihumans aren't human yadayadayada...
I think some chinese cultivation female power fantasy do have these topics tho. Just forgot which ones exactly
Just write nobody might judge you or flame you.
As an honest opinion if you are going to stick with you know those genres then dont expect to please everybody many like to read mindlessly and only enjoy power fantasy.
TWA is pretty good at explaining you how to deal with displeased readers