Ye, but it depends more in your personality and ofc in sexual preferences too, but mostly (the ones i had at least) perform their role depending on which one is more active in bed, the one that takes the lead, but not always cz they can explain and expect you to do how they say or its just a one night thing. Its different when you use the belt, the roles are easily differenciate, there are girls that prefer only to use the belt, only to recieve or being both.
The line between top and bottom for lesbians is way more neutral than what most of people think just by judging their appearance, people usually think that the butch ones are the "tops" when they most likely are not so brave in bed
Idk man both can be bottoms or tops while having sex without having to change positions like men do. It can change every time. Depends on the day, wether they have the humor or not to be one or the other, and also on how the sex goes, js let it flow(but sure there are ones that are only one by rule)

I'm curious, does the concept of Top and bottom exist in wlw relationship in real life?