Yes or no, depending on some factors that are worth explaining.
Your earnings will always be based on your netspace as a fraction of total netspace.
Therefore, over a long enough period of time, you are likely to win the same amount whether you farm solo or as part of a pool.
However, the aforementioned “long enough period of time” could mean hundreds of years. Considering that kind of timeframe, yes, you’ll probably earn more by joining a pool - because by the time your computer wins a block, you might be deceased :(
On top of that, pools will typically take a percentage of wins in order to pay for their costs. These fees will typically be small, in single-digit percentages, but necessary in order to pay for the labor, regulatory compliance, and technical expenditures required to keep the pool’s service running.
Overall, there is a very good chance that you will earn more by joining a pool, but it is not guaranteed.