Here you can check out Opensea's metadata standards which have some info on SVG standards for their site: https://docs.opensea.io/docs/metadata-standards
This is what they say about the image properties of your NFT metadata
image: This is the URL to the image of the item. Can be just about any type of image (including SVGs, which will be cached into PNGs by OpenSea, and even MP4s), and can be IPFS URLs or paths. We recommend using a 350 x 350 image.
image_data: Raw SVG image data, if you want to generate images on the fly (not recommended). Only use this if you're not including the image parameter.`