Grout sealer [bathroom & kitchen]

My daughter just rented an apartment with ceramic tiles in the kitchen, down a hallway & in the bathroom.
I recommended she get some grout sealer for it now that she's gotten it clean. [price of 'cheap' apartment]
Is there a superior sealer for either/both areas?
I've got tile in my bathroom and sealed it 20 years ago- and it has held up fine- but there is little traffic in there.

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