SEO is SEO
Luckily SEO is SEO no matter what platform you choose. Some platforms (like WordPress) have good practices with their code from the beginning and get you an extra start but there is still a lot of work that has to be done to get WordPress in the top ranking spots.
Tips

Here are some articles for Squarespace specific SEO tips:
- https://support.squarespace.com/hc/en-us/articles/205814568-Increasing-your-site-s-visibility-to-search-engines
- https://support.squarespace.com/hc/en-us/articles/360002090267
- https://support.squarespace.com/hc/en-us/articles/206744067-What-Squarespace-does-for-SEO
- https://support.squarespace.com/hc/en-us/sections/115002931768-Improving-your-SEO
- https://www.stylefactoryproductions.com/blog/squarespace-seo
- https://www.websitebuilderexpert.com/website-builders/squarespace/squarespace-seo-review/