All I'm gonna say is that I once hosted a one-shot game where half the party was Large-sized: an ogre, a minotaur, and a centaur were all in the party, along with a medium tiefling and a medium half-elf. And it was perfectly fine.
How did I do it? I changed the grid from 1 square = 5 x 5 feet, to 1 square = 10 x 10 feet. That's all.
Everything scaled up accordingly (all areas, ranges, etc., were converted to "squares" and played accordingly. "Range 30 feet"? That's 6 squares.) Medium-sized creatures still occupied "one square," but so did Large-sized creatures. It didn't break the game, even though it doubled the ranges, movement rates, and areas of effect. Characters were still moving 6 squares per turn, still able to reach adjacent creatures, still had darkvision out to 12 squares, etc., regardless of their size.
We didn't have Small characters in the party, but if we did, I would have treated them like I do Tiny creatures on a 5' grid.