A toddler is not going to sit through dinner. The goal is not stillness — it is giving them a part in it.
Not an activity to keep them busy — a job. Carrying the napkins. Putting the cover on the challah. Handing out the cups. A child doing a real job is calm in a way no colouring page achieves, because the table actually needs them.
This is the shape that works and it is worth stating plainly: a thing the child makes, that the family then uses. A challah cover they decorated on Thursday is watched all through Friday dinner. A colouring page handed over at the table is finished in four minutes.
Lower the lights. Slow down. A toddler reads the room long before they understand the day, and a house that moves differently on a Friday teaches Shabbat more effectively than any explanation.
Carry something unbreakable, put a cover on, press a napkin flat, choose which cup is whose. The job needs to be real and small.
That depends entirely on your household's practice and it is not ours to rule on. Families observe differently; make the things beforehand if that fits your practice.
Part of our guide to Shabbat with young kids.