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Yes.

Muscle cells have several nuclei.

Hepatocytes (liver cells) have usually one single nucleus, but, occasionally, we observe some of them with two nuclei in normal conditions.

When fighting some kinds of pathogens, usually large ones, such as helminth parasites, the "multinucleated giant cells" are formed, which are kind of a macrophage megazord.

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In other cases, are multinucleated cells usually cancer?

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Yes. Cells may become multinucleated cells if something goes wrong during the cell division/fusion which is possible when cancerous cells divide way too often unregulatedly.

The technical term is syncytium.
Some other people mentioned a couple of things, but the placenta is particularly interesting because there is evidence that is arose as a result of co-option of a viral gene. Some modern viruses cause syncytium formation in host cells as part of their life cycle.

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Yes, if the cells morphology is different than the normal cell, and it’s not specific just to the nucleus, can be shape or size as well or behaviour

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> Some modern viruses cause syncytium formation in host cells as part of their life cycle.

i.e. in the news we hear of flu, covid, and RSV

RSV = respiratory syncytial virus

The virus that spread simply by causing neighboring cells to merge.