For installing mods on Java Edition you need a modloader, there is no way around it (Forge, Fabric, Liteloader, and consideration of which version your wanting to play, 1.12.2, 1.14.4, etc. 1.12.2 and 1.14.4 for example are not compatible, some times like with 1.9.4 and 1.10.2 cross compatibility was a thing but for Forge it's uncommon to have cross version compatibility, Fabric mods do have cross compatibility but it depends on the mod and more so throughout 1.14 to 1.14.4, not always 1.14 to 1.15.2 support). Once you install the modloader to your launcher after getting that modloader from their websites, put the mod in the mods folder (a 'mods' and 'config' folder should be created, the config one might later if the mod generates one, not all mods do have configs, configs are tweaks you can made like setting a feature from a mod you don't want from true to false or other things).
If you want a mod like experience but no modloaders go for datapacks, you download them, put them in your saves/datapacks folder (as simple as putting a resource pack or world into their appropriate folders) and work them out based on the details on the download page/files inside of the pack. Recipes you'll have a bit of difficulty with, without the page info (besides experimenting) unlike mods where recipes are registered and easy to view in JEI, NEI or REI.
Modpacks are to be installed with a Modpack Launcher (setup the Twitch, MultiMC, Technic, FTB, etc. launchers and just select a modpack to download, the modpack will be setup for you once it's done). The Vanilla/Mojang launcher is only useful when it comes to modding for installing the modloader and putting mods in the mods folder, modpacks and the Vanilla launcher have nothing in common and won't do anything. If you get a modpack from curseforge with a manifest and other files (which is standard for modpacks on curseforge to get packaged before unloading their files/following the mod downloading process) you'll want the Twitch launcher to import it.
For Pocket Edition/Mobile I think you need Block Loader or maybe things have changed, best to ask on the MCForums in that area of threads or try some videos on Youtube, I've never had Pocket Edition/known much about modding Minecraft on a phone so I don't know for sure if it's still the same, or if mods are for before the Bedrock version of Mobile.