It depends on your child. I have one who literally starts climbing the walls if they have a day off sport. The other is happier with less.
I always said swimming, for obvious reasons. Ballet, to teach them how to hold themselves, grace and discipline. Gymnastics, to learn how to fall and build up some physical awareness.
I think they started 30 min baby ballet once a week and gymnastics 45 mins at about 2. Then added in the swimming lessons at 5. Before that swimming was just us going on a weekend.
I didn’t think 3 x 30 mins was much, but i did meet one mum who was horrified, called me pushy and said she would wait until her child expressed an interest. Which by the time the kid was old enough to do so, all local classes were full.
We stuck to that until they were 7 or 8, then they gradually started doing more of one and less of another until. They’re teens now and still very physically active which i think is very important, especially for girls.
Depending on their age i’d start with a variety of once a week short classes, and find out what they love. Ballet, swimming, gymnastics, martial arts are good foundations for any sport, brownies, music etc also.