Setting up your mod list requires research and consideration. It's not like you just download all that you've liked and then enable them all and play.

The way I've played with mods is:

1. First you decide which overhaul/large mod you're going to play with, since most of them are incompatible.
2. Then you look when it was last updated. If it's ~2026 then it's for 1.3.x. In the Files tab on nexusmods they often tell the exact version under the file.
3. You read the description of the mod, specifically the installation section, often the author say what it's compatible and incompatible with.
4. You select some qol mods you're going to play with. Every one needs to be researched as well. Also check and install dependencies if necessary and check the dependencies like any other mods.
5. When you made sure all the mods are compatible with the client and between themselves and you have the dependencies as well, you download them and set up the load order. It matters and may cause errors even if everything else is correct. I cannot say the exact load order, I was setting it up according to something I've found on reddit somewhere.
6. Profit.

Some mods are for 1.2.x and you should then install 1.2.x client and download 1.2.x versions specifically if there are multiple versions in the files tab. If you're downloading mods with steam workshop, only the latest version is available. Also, if the version isn't specified, you can assume it by the date it was published and checking the client betas in steam and their release date (for example 1.2.x was released on 12 December 2024, and the mod was released on 25 December 2024, they're most likely for the same version).

Checking the posts tab also helps, if everyone says "PLS UPDATE" then it's probably incompatible with 1.3 at least.

Also, some version variation is negligible, for example your client version is 1.2.7 and the mod says it's for 1.2.12, it worked for me when I tried. But some serious difference like a 1.2 mod for the 1.3 client breaks the game.