A common misunderstanding I see from people who don't quite understand how Google Ads works is that optimizing a Google Ad campaign to increase performance is simply a matter of testing more landing pages... landing pages that don't really differ too much from each other.
Don't get me wrong, sometimes a new landing page variation can make a huge difference but unless you're changing and testing a major element of the page, like say the headline or price, a new landing page likely isn't going to make a big difference.
Also, "testing" requires your data reaching statistical significance , so unless you're willing to commit to the test long enough you're probably not going to be able to trust the test results. Without statistically significant data, the results can be chalked up to chance.
It's better to skip the "test" and just focus on making sure your landing page design is clean, easy to read, loads relatively fast and has clear calls to action.
It's also a great idea to create more personalized landing pages for any Google Ad Groups that are getting decent click volume but the existing copy isn't doing a great job "meeting the user where they're at".
Again, this only makes sense if there is significant click volume coming from this ad group and the keywords in that ad group are different enough to warrant a slightly more personalized version of the sales letter. No need to "test" this either, there's almost no scenario where making sales copy more relevant and personalized is going to be bad for conversions.
In most situations, it's much easier to lower your Google Ad campaign's cost per conversion by making keyword and bid adjustments in the Google Ad's dashboard, like I explain in this blog post, than it is testing a new landing page.
If after all of this, your still struggling to get the results you want from your campaign then you should be looking at your offer and product/market fit. There's something off about your offer.