Eat some of the same food
Take a bite of the food you want them to know. Let them see that it belongs at the table.
Eating is the invitation
You do not have to announce it. Eating it is the invitation.
Put the food on your plate as well as theirs. Take a bite while you talk about something ordinary.
Only food that fits them
Share from the same dish when it is safe for their age and allergies. Egg on your plate stays off theirs if egg is not part of their diet.
If they reach for yours, that interest is useful. Offer a piece that matches how well they chew.
No performance
You do not have to say “mmm” on a loop. A normal bite is more believable.
If you dislike the food, do not perform a fake love of it. Choose a new food you are willing to eat too.
A sentence you can say
“I’m having some too.”