Part-time job online: You can find your own part-time job online on major part-time platforms, such as text editing, language translation, online marketing, etc.
Handicrafts: If you like handicrafts, you can create and sell them yourself, such as crochet, hand sewing, jewelry design and so on.
Purchasing and selling on a commission basis: You can purchase daily necessities, clothing and other commodities for others through overseas purchasing or Taobao selling on a commission basis.
Tour guide and translator: If you are good at communication and interested in traveling, you can consider being a tour guide or translator, which will not only increase your income, but also expand your circle of friends.
Home-schooling: If you are good at a certain subject, you can offer online education courses on the Internet, or become a tutor and provide paid tutoring services.
Copywriting: If you have strong copywriting skills, you can provide related services on a part-time platform or your own website.
Personal Fitness Trainer: If you are good at fitness, you can consider becoming a personal fitness trainer and providing private course services.
These are just some common sideline options. Actually, there are many other sideline options. You should choose a sideline that suits your interests, skills and time, and at the same time, you should operate legally to ensure that your normal work and life will not be affected.