The answer to this is going to vary wildly from game to game. Some games just have percentage counters that go above 100% (Batman Arkham Knight for example goes up to 240%, though we don't have an official category for that). For other games, the category widely referred to as 100% doesn't actually include everything for whatever reason, so there's a higher % category that actually includes everything (sometimes this is also called Max%). For some games 200% simply means 100%ing the game twice in a row.
It really depends entirely on how the game works and/or how the community chooses to define 100%.
In one of my games, there's a % counter that shows at the end of the game. Objectives you're guaranteed to satisfy simply by finishing the game get to 80%. Optional and side objectives makes it 120%. So we have any% and 120% as our categories, doesn't make much sense to have 100% as that would be only some of the optional and side objectives rather than all of them. Why the developers made that add up to 120%, no clue.
Some examples from games I know:
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Crash Bash - For some reason the developers made it so that collecting all items, gems and trophies will result in 200% progression, which is actually the "real 100%". You can't stop at exactly 100% because it will be arbitrary.
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Crash Bandicoot 3: Warped - Similar, collecting everything will result in 105%.
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Hollow Knight - The base game has 100% progression. The DLCs "The Grimm Troupe" and "Lifeblood" raise the maximum progression in the game to 106%, and the DLC "Godmaster" raises the maximum progression to 112%. Each category requires you to play with or without the relevant DLCs.
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Castlevania: Symphony of the Night - While there isn't any category for that, fully completing the game will result in 200.6% progression.
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Donkey Kong Country 1/2/3 - The games have a max progression of 101%, 102% and 103% respectively.
