The centre-back, speaking during United's training camp in the Republic of Ireland, made clear that this summer is not a window for modest additions.
"This summer's going to be big, really, really big," Maguire said. "We need more players, we need better quality, we need players to come into the starting eleven."
United are third in the table with seven games remaining, on course for a Champions League return after a year out of Europe. Maguire sees that as both an achievement and a starting point.
"We're in a strong position. We've had a great few months under the manager. I feel like the squad is starting to look like something that is a strong squad."
He was direct about the squad's current limitations.
"We're not in Europe this year, we've played 40 games at the end of the season, and we definitely need a bigger squad next year."
On the title conversation, Maguire is measured but optimistic. He points to changes elsewhere in the league — uncertainty around Manchester City's direction following Pep Guardiola's exit, and Liverpool's struggles this season — as reasons to believe the picture has shifted.
"Over the last few years you've obviously had Manchester City, who were really tough to catch. I think next season, if we get the recruitment right, there's no ceiling to where we can reach."
He is clear-eyed about the task ahead, though.
"Come February, March, we don't want to be adrift like we have been this year. We don't really want to get carried away."
Arsenal lead the title race with seven games to play. United's hierarchy has targeted 2028 as the year to end a drought stretching back to Sir Alex Ferguson's retirement in 2013.
Maguire, for one, is not prepared to wait that long.