There is not a straight answer to this. But probably the answer in your case is “no”.
Loco Translate has no knowledge of your site, or how many languages you want to display. It is a PO file editor. It can be used to translate anything that is in a PO file. Generally that means static text in themes and plugins, and the WordPress core. You can do this in multiple languages, but that won’t make your site multilingual because Loco Translate does not control this.
WordPress sites are not multilingual. Each site is set to a single language. A multisite installation will allow each site to have a different language setting.
If you are after a plugin that will make a single site into a multilingual one, and let you translate all the content in the database, then Loco Translate will not help you do that.
You will have to either set up three sites under multisite, or find a plugin which will enable the multilingual functionality you need. These exist, but I am not in a position to recommend any.
