However, in my layman's opinion, the real estate agent knows best how to assess the market.
But if two real estate agents differ by 50% in their estimate (or their guess), that shows that the agents just DO NOT know how to assess it. Either only one or both...
What’s actually so difficult about just looking up similar properties (age, size, similar location, plot) on Immoscout, Immowelt to get your own "feeling" for the price? You can even do that at home from the sofa. When you buy a car, you also compare the price lists of, say, a 3 Series, A4, and C-Class without letting anyone talk you into anything.
You can then easily make a list, calculate the asking prices per m2, roughly estimate the plot sizes (easy if you have a land value reference online, e.g., Boris), and write the pros and cons of your own house as a comment next to it. That way you quickly get a sense of the asking prices compared to your own.
If you don’t feel like dealing with all the negotiations, viewings, and buyer questions, you can still hire an agent afterwards. Preferably one whose price estimate is in relation to the own experience you’ve gathered in a similar area.
P.S.: There are always agents who want to sell well below value. That usually speeds up a sale, you only have one viewing appointment, and the agent’s effort is significantly less. If I get 75% of the pay for 25% of the time, that’s also a business model.