If you have a signal generator, you can do something like this,
https://www.seventransistorlabs.com/Calc/RLC.html#frqThe numbers are exact for sine wave; you can use a square wave still, but the source voltage will be somewhat in error (if it's a 50% duty, bipolar (symmetrical +/- V) square wave, the fundamental peak is 4/pi times the square wave peak (not p-p!) voltage).
Typical values might be 0.1uF and 1kohm. Don't forget to include source resistance (of the generator) -- or, measure the voltage on both sides of the resistor, when at the resonant peak frequency.
You'll usually need an oscilloscope to do this, but you can still get the frequency right by, well, anything that can measure/infer the frequency, and using a peak detector to qualitatively measure the tank voltage (you just need to find the peak). (A DMM will not have high enough frequency response to measure the voltage here.)
So, the most basic case could be an Arduino generating a square wave, and you have a console or debug interface to tweak the period up or down as you find the resonance. A peak detector can be any signal diode, into a parallel RC network to GND, say 10nF and 100k, then measure the DC voltage on it with a DMM.
Tim