A tea party is always fun, and combines well with other fun things like dressing up, making a cubby and cooking. But you don’t need to bake in order to have a tea party.
Make a pot of tea. Then fill a small metal teapot with cold water and let children add cold water to the hot tea you put in their cup. Use herbal tea if you don’t want them drinking tea, though it’s very watered down by the time they drink it. The food, which you can prepare together, might be patty cakes but it could be sliced fruit, dried fruit, crackers and cheese, etc. Present the food on small plates and give kids their own little teacups so it feels like a special occasion. A tiny jug of milk could also be part of the setting. A tablecloth is nice but will likely end up wet until kids develop pouring skills. Secondhand shops are great places to find these things for next to nothing – don’t use your heirloom china.
Why not invite a friend or relative to tea? Or the neighbours if you’re being spontaneous. At the very least some dolls and a teddy or two.