While I don’t have an iOS device to check this it does seem like there are new units for viewport height including svh, lvh, dvh and these might solve your problem.
This might also be something Wix could improve and offer in the editor.
You could try assigning classes to these sections and then specifying their height in these units. Example:
.bottomBar {
height: 15dvh;
}
.section {
height: 85dvh;
}
Some more info here: