Standard short texts aren't delivered by mobile data, they're messaged as packets within the voice stream and wouldn't involve mobile data. Multi-media message content is different so anything longer than the network permits would convert to MMS, as would photos, videos and graphic emojis. If you've got mobile data off you shouldn't be able to send or receive MMS or text. You might be able to get MMS and mobile data via wifi calling, but that depends on your operator, phone and the connection. Watch out for charging of standard texts internationally - mobile networks are always keen to fleece their customers.
And for clarity, this is a UK Virgin Media forum, so although the above will apply to Virgin Canada, most of us have no idea what roaming arrangements would apply for you, or the detail of how Virgin Canada price and handle texts.
