Our children are trilingual.
It takes a lot of effort to achieve fluency. They are fluent in two out of three languages.
The children have been taught two home languages and cultures from birth.
The third language has been taught from reception class. The 3rd language was childrens' own choice to pass time under covid. Not a mother tongue language for us but parents do speak and understand it well.
In everyday life the children need lots and lots of conversations, lots of interaction with people speaking the languages, lots of books/comics/games/audiobooks/films to work with.
Take them to see theatre perfirmances in the target language/s. Watch Disney movies in the target language/s in the cinema.
Regular visits to relevant countries (see family if possible) so very useful.
Mayby summer schools or camps (which can be expensive).
Ours go Girl Guiding/Scouting jamborees in summer to strengend their language/s and bonds with Girl Guides/Scouts culture in their two first languages. Needs some travelling.
Our children have online tutor lessons 60 minutes twice a week in second and third languages. It's works brillant for them/us. They are assigned homework each week. They enjoy these classes and work pretty hard. It can take some research to find the right match between teacher and pupil.
Their first language is 100% fluency.
School language at the moment.
just changed a few weeks ago as we relocated at Christmas.
Second language is a very high fluency. They use it daily. Do leisure classes in this language and have friends their own age.
it has been school language for years. Now we have to keep up the level.
Third language - the basic is working and being developed. Not used much in everyday life but well above over expected performing level in their new school the teacher tells us.
We relocated at Christmas to an EU country from 20 years in UK.
3rd language in new country is a mandatory subject and they do very well. The native children have been taught a year of curriculum at this point and school expected nothing of our children. Thank you, Covid.
They are taught the national language of course, English as 2nd and German (or French) as 3rd - which fit our children well.
But tbh raising bilingual children is a very big commitment and often hard work. But very rewarding!
FB has some great groups for parents with children with multiple languages.
We have been in this game for the long run. The oldest two children are +18 yo are at university and the youngst in secondary school.