S-Log and Rec 7.09

I'm not sure I understand what you want. Do you want to normalize (convert from log to "linear" display data) manually, or just turn down the amount of change? And do you want this on all clips or only on some?

Whatever you want to do, the controls are in the Lumetri panel's Settings tab, the tab at the top of the Lumetri panel named Settings. 

That is where you would work to test settings. I'm out on the road without computer, so I can't check. And I think you can use the "override-to" options to change some things perhaps even with both auto detect log and auto tonemapping on.

Which camera are you working with, and what log setting? I would note that on some of the mid/lower end Sony cams, there is a "variant" option for S-log3 that isn't actually log-encoded. It simply applies the lowest camera contrast and saturation settings to the file, but the data is "regular" Rec.709 mathematically. That's a bugger that trips up many users. Make sure your log is log.

Normalization of log encoded media is both science and art. There's both technical parts to it, and always, even in the maker LUTs from camera makers, there are aesthetic choices. LUT based normalization can induce issues, and so most colorists using that process always include the LUT in a second node, and use the first node to "trim" the clip's exposure, contrast, and saturation, to fit what the LUT was built to work with.

The newer built-in algorithmic transforms in both Premiere and Resolve are mathematically superior transforms. They can use complex mathematical formulas that do not risk clipping, crushing, or over-saturation to a channel. Hence preferred by many colorists.

Like all normalization options, as there are both technical and aesthetic choices in building them, the normalization process is only a starting point. It is assumed the user will modify to whatever they prefer.

In Premiere it's easy to make Lumetri presets that can be applied in bulk to clips in a bin. Even un-applied and replaced quiclky, so you can try A, B, then C, and especially with large thumbs make a quick estimation of which preset you'd prefer on which clips.

So I stick with the algorithmic transforms with any media Premiere recognizes. I've tested this with perhaps everything they do work with. The algo's seem at least as good as any LUT, and test totally safe.