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Yes, You are good to go, further, you can add comments before each domain starting with the "#" sign. your notepad file name should end with ".txt", maximum URL length is 2048 characters, ad a single file could have 100,000 lines (including blank lines and comment lines) and 2MB.
Source: https://support.google.com/webmasters/answer/2648487?hl=en
Regards: https://www.unlockninja.com/
there are customized pages on the client's site, they contain brand pages related to Samsung, iPhone, ZTE, LG, Motorola, and HTC Mobile phones.
For Example:
https://www.unlockninja.com/unlock-apple+phone
https://www.unlockninja.com/unlock-zte+phone
https://www.unlockninja.com/unlock-samsung+phone
Should I recommend them to change the URL structure. ?