i don't quite understand what you mean by that.
1. industrial sensors have certain ratings including operating voltage and you better stick to the specs. i don't recall proxy sensor that will operate on less than 10V.
2. you do not get signal level equal to supply voltage of the sensor. sensors like this may be called a 'switch' but unless they have relay output, you do not get output that is comparable to mechanical switch. PNP output sensors powered by 24V, have output of maybe 22V. without any load you may read that as something closer to 24V but again, without load, this is hardly usable. reason for significant drop is configuration of the output circuit - even though it is commonly referred to as "PNP" it is not an open collector PNP but rather common collector NPN (just like in UDN driver arrays). one of the reasons is that this configuration offers some protection.
3. things mentioned in 1 and 2 are about sensors (they are used as inputs to MCU). when you mention TIP41C, i guess you want to use it with an output of a MCU (please clarify). in that case you need to identify few things like load current, transistor, gain, voltage level of MCU output, current rating of MCU output etc. in practice it is common to assume that gain is 10 so that transistor is in saturation when on. in simplest case one would compute base resistor using Ohms Law:
R = V/I
where
R is resistor value in Ohms
I is resistor current (not more than max current MCU output can handle)
V is voltage drop across resistor. it can be computed as difference between MCU output level and Vbe of a transistor.
for example some arbitrary MCU is powered by 5V, outputs are at 4.5V when high while driving max output current od 20mA.
assuming your transistor has Vbe = 0.7V then smallest resistor value is
R>= (4.5-0.7)/0.02 = 3.8V/0.02A=190 Ohm.
since we assumed gain of 10, this will work fine with load that draw I=20mA*10 = 200mA
driving 'PNP' output stage with supply voltage such as 6-36V you need level shifter. in simplest form that would be two transistors and two resistors. basically it is just cascade of what we just used, the only difference is is that second transistor is PNP (which also adds to gain of output stage) and it connects to output power rail (6-36V in this case).
either way, finding the best depends on what you want to do with it. if you need more help, you need to be specific.