I did mine in Spain in 1979 and back then (and in my school, run by nuns) mums could choose between a white tunic (very similar to the nun's habits but white instead of grey) or what the called "a Maria dress", which basically was a short sleeved white silk or cotton dress with minimal detail. Shiny fabrics, veils, bags or extravaganzas were not permitted. For boys the typical thing was a white tunic (altar boy style), a sailor suit or the school's uniform. I was in a white tunic as my mum thought the "Maria" dress would not have any use (I am very pale and looked and still look like a ghost in white clothes). But I would have wanted a "Maria" dress.
I have attended many FHCs in Spain in the past few years (my nieces and my Spanish friend's children) and the clothes are still the same, although some of them look much more expensive (fabrics, cut...). I have never seen any little girl looking like a bride. They are just little girls in white dresses.
However nowadays in Spain they have big parties afterwards (in my time it was just family and the FHC child's friends) with (in my view) expensive and fairly useless add-ons, as personalised sweeties and cupcakes table, a couple of entertainers and even photocalls with professional photographers...
Presents, back in my day, were related to the sacrament (missal, medal, rosary...), small items of jewelry (earrings, bracelets) or useful (books, a watch, a guitar, a camera...). The gifter usually asked the mum or grannies before buying anything. Nowadays there are FHC lists which include clothes, sportswear, tablets and smartphones...
Back here, my boys wore smart trousers and jacket and my girls (who had theirs at the RC school they attend) white tunics, although they were allowed to wear white FHC dresses underneath (anything with petticoats was kind of out of scope, btw).
I still think that FHCs in Spain are much more extravagant than here however I have never seen a limo and children are dressed much more nicely.
Just for context, the FHC is in the year the children are or will be 9 or 10 (depending on every bishop's orders; in the area I am from it is 10) and they have had to go to the local church catechesis for the three previous years (usually a session per week plus the Sunday Mass for children). In some places the parents also have to attend a much short course for parents in the year their children are having their FHC. Things change from bishopric to bishopric but in some places catechesis and FHC still can take place in RC schools.