There are two options here:
1. LSI keywords (which as the industry knows them today are complete garbage).
- Most LSI generators simply give you variations of the primary keyword. Use those too much and risk your kw density reaching a spammy level (i.e. Red Widgets, Large Widgets, Best Widgets...)
2. Real Semantically relevant concepts and topics
- Think industry relevant topics. If I'm a gym, relevant topics include: fitness apparel, supplements, diet, etc...and all the keywords that go with them
- Semantically diverse links (and more importantly on page content) is a key quality signal for the Google of today
If anyone is interested in a unique way to balance out or modify your existing link ratios / anchor text ratios on-page for up to 1000s of historical posts automatically hit me up. We're bringing a product out of alpha and into beta soon for Wordpress based sites that is an SEO behemoth. Sites using our plugin have consistently seen double digit increases in traffic and on-page engagement.
Regards,