Short answer: often yes, but it depends more on footprint and platform count than on the tower simply being "big enough."
What actually matters for sharing
Two large cats sharing a tower need enough separate platforms that neither has to challenge the other for a spot — a tower with only one or two usable perches tends to create competition regardless of overall size. Look for multiple distinct levels, and ideally more than one enclosed retreat, not just one large open platform.
Personality matters as much as design
Some cats happily co-exist on the same structure; others prefer clearly separate territory. If your cats aren't naturally inclined to share, a single tower — however large — may just relocate the competition rather than resolve it. Watch how they actually use shared spaces already in your home as a guide.
What to look for when buying for multiple cats
Multiple enclosed condos, more than two open platforms, and a wide base for stability under two cats' combined activity all help. See managing a multi-cat household with large breeds for more, and browse multi-cat-suited towers in the Maine Coon Collection.
FAQ
How many platforms does a tower need for two cats?
More than two is a reasonable starting point, ideally with at least one enclosed retreat each, so neither cat has to wait for a spot.
What if my cats don't get along on the same tower?
Consider two separate, smaller pieces of vertical furniture in different parts of the room rather than forcing them to share one structure.