There are many factors for the ranking improvements, to improve the ranking of your specific keywords from positions 50-100, it's essential to approach the task with a combination of on-page optimization, content improvement, and a strategic off page plan.
You should work on building high-quality backlinks to improve the authority and ranking of your pages.
This is an important question - What should be anchor text diversity strategy?
To avoid penalties and make your backlink profile look natural, diversify your anchor text. You can use this Anchor Text Diversity Strategy
Exact Match: 10-15% of your links should use the exact keyword you want to rank for.
Partial Match: 15-20% should use variations or longer phrases that include your keyword.
Branded Anchors: 20-25% should include your brand name.
Generic Anchors: 10-15% can use generic terms like "click here," "read more," etc.
Naked URLs: 15-20% should be the URL of your page without any anchor text.
LSI (Latent Semantic Indexing) Keywords: 10-15% should use related keywords or phrases.
For the type of backlinks
PBN Links: Be cautious with PBNs as they can be risky. If you use them, make sure they are high-quality, relevant, and not part of a detectable network. Limit the use of exact match anchors here.
Guest Posts: Focus on high-authority, niche-relevant sites. Use a mix of anchor texts with an emphasis on branded and partial match keywords.
Web 2.0 Properties: Create content on Web 2.0 sites and use them to build links back to your pages. Use more generic and naked URL anchors
I hope this works for your. Best of luck.
