Yes. Spinach and Tomato have a documented companion-planting benefit. University of Minnesota Extension suggests early lettuce, spinach, or basil in beds that later hold tomatoes for succession, weed management, and soil cover.
This is a practical yes, not a magic guarantee. Keep the normal spacing for Spinach and Tomato, watch airflow and watering, and treat the companion note as one useful planning signal alongside sunlight, soil, and harvest timing.
Source basis: University of Minnesota Extension companion planting guide. The page does not add extra pest-control or yield claims beyond the sourced fact row.
Spacing tip: Keep airflow around the larger crop and place the smaller crop at the edge of its drip line.