Proportional / relative tempo marks

Is it possible to do Tempo marks such as “Quaver = quaver”; “dotted semibreve = semibreve”?

Or for now, do I just use Text? (Though on I’ll need it on each part, but not every staff in the score.)

Not yet. Search the forum, there are several threads about it, and one with models already given
https://www.steinberg.net/forums/viewtopic.php?f=246&t=134237&p=726848&hilit=Tempo+equal#p726848
https://www.steinberg.net/forums/viewtopic.php?f=246&t=124943&p=677836&hilit=Tempo+relative#p677836
https://www.steinberg.net/forums/viewtopic.php?f=246&t=118314&p=643012&hilit=Tempo+modulation#p643012

Thanks, Marc. System Text is it. I tried searching, but lacked the terminology!