What are the "non-standard" hypotheses for increasing conversion?

Question

Marketing

Good afternoon. Can you please tell me what are the "non-standard"/unpopular hypotheses that can be tested to increase the conversion to checkout?
To make the question more clear, I will give a little understanding of what I mean by standard:
-optimization of the page code for faster loading
-breadcrumbs -big
"buy" button
- discount for registration, etc.

Answer 1

Well, take a look here