Yes, one can eneter a FIDE tournament at any age.
Most FIDE tournaments are open to all ages.
There are some special tournaments: -20, -15, +55, +65.
Can one enter FIDE tournaments at any age?

So these -20 -15 65+ etc are special, and they constitute what% of the tournaments roughly? And the open to all ages are what %?
@3
I guess > 90% are open to all ages.
See for yourself: https://www.fide.com/calendar

I love chess age 63 ,and i will win
But never have to las vegas ,Nevada to play
Gambling ,what most people go for and Entertainment ,Food and slot machines
Rolling the dice too
Chess is my most favorite ,game
Always love a good challenge ,never afraid too lose or learn If i got the money ,put it up
I have played online and 90 percent of the times i won, a lot of people , i have beaten chess online Chess.com
Magnus sleeping ,i beat him 8 moves gave queen up then won ,i only played few times then
Stopped but if i do come to las Vegas i am sure to win
Im nearly 20, and have no experience in otb tournaments, have only played online since 2020, but want to enter them at some point, all i see is kids entering tournaments, are there tournaments for adults? How does it work? Someone please give an overview. Thanks!