If you are serious about photography and photo editing, you are definitely in need of more than a phone or tablet for the latter. If you are a professional, you probably rely on software from Adobe or others. If you are a casual user, you can find built-in dedicated programs in both Windows and macOS, each called Photos. These are good for quick edits, but the more complex it gets, the harder it is to work with these software.
Beginner and Intermediate: Adobe Lightroom
Lightroom has a simple set of menus and easy workflow compared to Photoshop, with a Classic option that has suited to desktops. Classic is more powerful than the Lightroom CC app, which is meant for mobile editing. After you have exhausted the built-in editing tools this software has to offer, you can turn to the internet, where you will find downloadable presets made by photographers, which can be added to the program for a better look to the photos. If you are inclined towards stylized edits over small adjustments, or wish to automate most of your work, Classic is the way to go.
If you have a less intensive editing style, it is best to go with Lightroom CC. The UI of this is a lot similar to the mobile app, and additionally, any photos that are imported into the app on the phone get synced with the Creative Cloud. That means you can take a photo on your phone and start editing it on your iPad, then finish up the work on your home PC. A single subscription gives you access to both Lightroom Classic and Lightroom CC.
Advanced: Adobe Photoshop
Sometimes you will need to work deeper than what Lightroom allows for, which is when Adobe Photoshop comes into play. You can do all your heavy stuff here, like removing a tree from a flat horizon, or bringing people closer together, or myriad other stuff. Photoshop also functions as a graphics creation program, so if you have the time, you can get the best digital images on your hands.
No Subscriptions: Affinity Photo
At a cost of $50 with free updates, Affinity Photo brings a similar UI to Photoshop, such as layer tools, RAW editing, digital painting, and batch processing. There is even the option to edit 360-degree photos. The similarity with Photoshop means that with a few days of tinkering around and a handful of YouTube tutorials, you can learn your way around the use of Affinity Photo.