Bachelorette Party

Normally, you don't invite people to pre-wedding events that aren't invited to the wedding itself. You don't want there to be the perception of "tiers" of guests - like half of the guests at this event are "tier A" and made the list for the wedding and the other half are "tier B" and didn't. You wouldn't feel that way, of course, but it could seem that way to them.

If the size was reduced because of COVID, all rules should be thrown out the window and you should do whatever feels right.

I agree with this. If the size was reduced due to Covid, and your aunts were on the original invite list before Covid, then absolutely I don't see the problem with inviting them. If you were only having around 50 people to begin with and they didn't make the original cut, then I wouldn't invite them to any pre-wedding events.

If they're aware you had to cut due to COVID and not budget constraints/other constraints I think it would be okay to invite them. Typically though you do not invite someone to wedding events if they aren't invited. Have you considered having the wedding streamed via zoom so they can feel a part of the ceremony and big reception moments?