Unfortunately not.
Bars are a bit deceiving. There are two reasons why your bars might be low. Knowing which it is will determine which booster you should purchase.
Low signal strength: For 4G LTE networks, signal strength is called "RSRP" - Reference Signal Received Power. If your RSRP is less than -80 dBm (e.g. -90 dBm or -100 dBm), your signal is weak.
Low signal quality: For 4G LTE networks, the measure of signal quality is "SINR" - Signal to Interference Plus Noise Ratio. If your SINR is less than 5 dB (e.g. 2 dB or -1 dB), your signal is low quality.
If you take outdoor signal measurements, you'll know exactly which of those applies. It may be one, both, or neither.