You tell them you want your lawyer and you will not answer any questions until you see them. Your lawyer will tell you how to proceed.
If the police have nothing on you and wanted to fish something out of you, your lawyer will get you free. If the police have something against you and are pursuing further, your lawyer will inform you of what your options are. But generally, this is when you’re going to have to deal with this shit. It doesn’t matter if you did it or not at that point, but a lawyer will be your best bet to make it out on best grounds - whether that is get out free or with the smallest fine/sentence.
Just know:

• if the police has something on you, and you did it, its game over, a lawyer may help ease the price you pay
• if the police has something on you, and you didn’t do it, its an unfortunate situation, a lawyer may help ease the price you pay
• if the police has nothing on you, and you did it, though unethical, a lawyer will get you off free
• if the police has nothing on you, and you didn’t do it, a lawyer will get you off free