There are 2 ways of looking at the situation here. Joining as an individual UX designer in a company with no design team can be an opportunity to define the design strategy and direction for them. It will be the challenge as well as learning; you will be able to take decisions, drive design and product strategy and build the team. Of course, you will be handling all the work; ideation, prototyping, designing and communicating with developers. But that will be a great way for you to grow and execute complex ideas and build your decision making, management and design skills.
On the flip side, if you can’t handle the pressure, you will be buried under a lot of work and responsibilities. You will be solely held responsible for all the decisions made and sometimes, that can be scary if you are not prepared to handle delicate situations.
In conclusion, if you are prepared for the barrage of work, do join because it’s an opportunity to grow and learn a lot. If not, start out in an organization with a team, gain the skills and then join another company and lead the design strategy.